Pub Date : 2024-11-17DOI: 10.1021/acs.jpcc.4c07053
Ozan Baran Orhan, Nahit Polat, Seren Demir, Fadime Mert Balci, Sinan Balci
Nanoporous gold (NPG) films are three-dimensional gold (Au) frameworks characterized by a uniform distribution of nanoscale irregular pores. Typically produced via a dealloying process, where the less noble silver (Ag) is selectively etched out, NPG films offer a large surface area, excellent chemical stability, remarkable catalytic activity, unique optical properties, and biocompatibility. These attributes make them invaluable for applications in catalysis, plasmonics, biosensors, and nanophotonics. However, the presence of residual Ag from the dealloying process can limit their performance in certain applications. In this study, we report a novel method for the fabrication of ultrapure, large-area NPG films (several cm2) using a light-induced and liquid crystal-templated method. A hexagonal lyotropic liquid crystal containing a strong acid and a nonionic surfactant is combined with an aqueous solution of HAuCl4, followed by the photochemical synthesis of gold nanoparticles (NPs) within the liquid crystal. After calcination of the Au NP-containing liquid crystal film at high temperature, pure NPG films are produced. We demonstrate surface-enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) molecules adsorbed on the NPG films and detect extremely low concentrations (below 10–6 M) of R6G. Additionally, we thoroughly investigated the formation and optical properties of the NPG films. The results reveal that the ultrapure NPG films contain high-density plasmonic nanocavities, where substantial electromagnetic fields are generated, leading to significant enhancement of optical processes at nanoscale dimensions.
{"title":"Light-Induced, Liquid Crystal-Templated Fabrication of Large-Area Pure Nanoporous Gold Films with High-Density Plasmonic Cavities","authors":"Ozan Baran Orhan, Nahit Polat, Seren Demir, Fadime Mert Balci, Sinan Balci","doi":"10.1021/acs.jpcc.4c07053","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c07053","url":null,"abstract":"Nanoporous gold (NPG) films are three-dimensional gold (Au) frameworks characterized by a uniform distribution of nanoscale irregular pores. Typically produced via a dealloying process, where the less noble silver (Ag) is selectively etched out, NPG films offer a large surface area, excellent chemical stability, remarkable catalytic activity, unique optical properties, and biocompatibility. These attributes make them invaluable for applications in catalysis, plasmonics, biosensors, and nanophotonics. However, the presence of residual Ag from the dealloying process can limit their performance in certain applications. In this study, we report a novel method for the fabrication of ultrapure, large-area NPG films (several cm<sup>2</sup>) using a light-induced and liquid crystal-templated method. A hexagonal lyotropic liquid crystal containing a strong acid and a nonionic surfactant is combined with an aqueous solution of HAuCl<sub>4</sub>, followed by the photochemical synthesis of gold nanoparticles (NPs) within the liquid crystal. After calcination of the Au NP-containing liquid crystal film at high temperature, pure NPG films are produced. We demonstrate surface-enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) molecules adsorbed on the NPG films and detect extremely low concentrations (below 10<sup>–6</sup> M) of R6G. Additionally, we thoroughly investigated the formation and optical properties of the NPG films. The results reveal that the ultrapure NPG films contain high-density plasmonic nanocavities, where substantial electromagnetic fields are generated, leading to significant enhancement of optical processes at nanoscale dimensions.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"99 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142665340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hydrogen adatoms are involved in many reactions catalyzed by Transition Metal (TM) surfaces, such as the Haber–Bosch process or the reverse water gas shift reaction, key to our modern society. Any rational improvement on such a catalyst requires an atomistic knowledge of the metal↔hydrogen interaction, only attainable from first-principles calculations on suited, realistic models. The present thorough density functional theory study evaluates such H interaction at a low coverage on most stable surfaces of bcc, fcc, and hcp TMs. These are (001), (011), and (111) for bcc and fcc TMs and (0001), (101̅0), and (112̅0) for hcp, covering 27 TMs and 81 different TM surfaces in total. In general terms, the results validate, while expanding, previous assessments, revealing that TM surfaces can be divided into two main groups, one in the majority where H2 would be thermodynamically driven to dissociate into H adatoms, located at heights of ∼0.5 or ∼1.0 Å, and another for late TMs, generally with a d10 electronic configuration, where H2 adsorption with no dissociation would be preferred. No trends in H adsorption energies are found down the groups, but yes along the d series, with a best linear adjustment found for the d-band center descriptor, especially suited for close-packed fcc and hcp TMs surfaces, with a mean absolute error of 0.15 eV. Gibbs free adsorption energies reveal a theoretical volcano plot where fcc TMs are best suited, but with peak Pt performance displaced due to dispersive force inclusion in the method. Still, the volcano plot with respect to the experimental logarithm of the exchanged current density polycrystalline data is far from being valid for a quantitative assessment, although useful for a qualitative screening and to confirm the trends computationally observed.
{"title":"Atomic Hydrogen Interaction with Transition Metal Surfaces: A High-Throughput Computational Study","authors":"Miquel Allés, Ling Meng, Ismael Beltrán, Ferran Fernández, Francesc Viñes","doi":"10.1021/acs.jpcc.4c06194","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c06194","url":null,"abstract":"Hydrogen adatoms are involved in many reactions catalyzed by Transition Metal (TM) surfaces, such as the Haber–Bosch process or the reverse water gas shift reaction, key to our modern society. Any rational improvement on such a catalyst requires an atomistic knowledge of the metal↔hydrogen interaction, only attainable from first-principles calculations on suited, realistic models. The present thorough density functional theory study evaluates such H interaction at a low coverage on most stable surfaces of <i>bcc</i>, <i>fcc</i>, and <i>hcp</i> TMs. These are (001), (011), and (111) for <i>bcc</i> and <i>fcc</i> TMs and (0001), (101̅0), and (112̅0) for <i>hcp</i>, covering 27 TMs and 81 different TM surfaces in total. In general terms, the results validate, while expanding, previous assessments, revealing that TM surfaces can be divided into two main groups, one in the majority where H<sub>2</sub> would be thermodynamically driven to dissociate into H adatoms, located at heights of ∼0.5 or ∼1.0 Å, and another for late TMs, generally with a <i>d</i><sup>10</sup> electronic configuration, where H<sub>2</sub> adsorption with no dissociation would be preferred. No trends in H adsorption energies are found down the groups, but yes along the <i>d</i> series, with a best linear adjustment found for the <i>d</i>-band center descriptor, especially suited for close-packed <i>fcc</i> and <i>hcp</i> TMs surfaces, with a mean absolute error of 0.15 eV. Gibbs free adsorption energies reveal a theoretical volcano plot where <i>fcc</i> TMs are best suited, but with peak Pt performance displaced due to dispersive force inclusion in the method. Still, the volcano plot with respect to the experimental logarithm of the exchanged current density polycrystalline data is far from being valid for a quantitative assessment, although useful for a qualitative screening and to confirm the trends computationally observed.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"18 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642723","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1021/acs.jpcc.4c06136
Lauren M. Hoffman, Delaney J. Hennes, Pin Lyu
Metallic nanoparticle photocatalysts have been developed in various catalytic systems over the past few decades, including diverse noble and non-noble metals with plasmonic properties. The hot-carrier-induced mechanism is one of the most appealing pathways as it can provide energetic electrons or holes for driving thermodynamically unfavorable reactions or increasing the reaction rate. In this work, we evaluate the photocatalytic performance of semimetallic bismuth nanoparticles and offer detailed mechanistic interpretations in terms of hot carriers and interband transitions. The photocatalyzed nitrophenol reduction with sodium borohydride serves as a model reaction, and a wavelength-dependent study reveals the contribution of hot carriers. It is demonstrated that light irradiation under shorter wavelengths could produce deeper hot holes in bismuth nanoparticles, which can be quenched more effectively by hole scavengers, thus facilitating the electron-transfer process and resulting in larger apparent reaction rate constants. The observed photocatalysis enhancement accounts for the unique band structure with an extremely small band gap and exclusive interband absorption in the visible region. This proof-of-concept work offers a different perspective on the photocatalysis mechanism of bismuth nanoparticles and could help us better understand the role of hot carriers involved in photocatalysis, especially with interband transitions.
{"title":"Deciphering the Photocatalysis Mechanism of Semimetallic Bismuth Nanoparticles","authors":"Lauren M. Hoffman, Delaney J. Hennes, Pin Lyu","doi":"10.1021/acs.jpcc.4c06136","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c06136","url":null,"abstract":"Metallic nanoparticle photocatalysts have been developed in various catalytic systems over the past few decades, including diverse noble and non-noble metals with plasmonic properties. The hot-carrier-induced mechanism is one of the most appealing pathways as it can provide energetic electrons or holes for driving thermodynamically unfavorable reactions or increasing the reaction rate. In this work, we evaluate the photocatalytic performance of semimetallic bismuth nanoparticles and offer detailed mechanistic interpretations in terms of hot carriers and interband transitions. The photocatalyzed nitrophenol reduction with sodium borohydride serves as a model reaction, and a wavelength-dependent study reveals the contribution of hot carriers. It is demonstrated that light irradiation under shorter wavelengths could produce deeper hot holes in bismuth nanoparticles, which can be quenched more effectively by hole scavengers, thus facilitating the electron-transfer process and resulting in larger apparent reaction rate constants. The observed photocatalysis enhancement accounts for the unique band structure with an extremely small band gap and exclusive interband absorption in the visible region. This proof-of-concept work offers a different perspective on the photocatalysis mechanism of bismuth nanoparticles and could help us better understand the role of hot carriers involved in photocatalysis, especially with interband transitions.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"98 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1021/acs.jpcc.4c06709
Koki Kannari, Aimin Ge, Chengyang Xu, Ken-ichi Inoue, Shen Ye
Recent studies indicate that concentrated electrolyte solutions can enhance the stability of organic solvents during the charge/discharge processes in lithium–oxygen (Li–O2) batteries. However, the effects of electrolyte concentration on the solvation structures of lithium ions (Li-ions) at the electrode surface and their implications for oxygen reduction and evolution reactions (ORR/OER) remain poorly understood. In this study, we investigate the solvation structures of Li-ions in bulk solutions and on a gold electrode surface at various concentrations of acetonitrile (CH3CN) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolytes, using in situ Raman and surface-enhanced Raman spectroscopy. Our findings show that increasing electrolyte concentration decreases the number of free CH3CN molecules, significantly altering solvation structures at the electrode surface. Decomposed CH3CN species predominate the gold electrode surface, while the irreversible side reactions are suppressed in highly concentrated electrolytes. This research highlights the importance of electrolyte concentration in optimizing solvation structures and enhancing the electrolyte stability of Li–O2 batteries.
{"title":"From Bulk to Surface: A Raman Spectroscopic Analysis of Solvation Structures in Concentrated Acetonitrile Electrolytes for Li–O2 Batteries","authors":"Koki Kannari, Aimin Ge, Chengyang Xu, Ken-ichi Inoue, Shen Ye","doi":"10.1021/acs.jpcc.4c06709","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c06709","url":null,"abstract":"Recent studies indicate that concentrated electrolyte solutions can enhance the stability of organic solvents during the charge/discharge processes in lithium–oxygen (Li–O<sub>2</sub>) batteries. However, the effects of electrolyte concentration on the solvation structures of lithium ions (Li-ions) at the electrode surface and their implications for oxygen reduction and evolution reactions (ORR/OER) remain poorly understood. In this study, we investigate the solvation structures of Li-ions in bulk solutions and on a gold electrode surface at various concentrations of acetonitrile (CH<sub>3</sub>CN) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolytes, using in situ Raman and surface-enhanced Raman spectroscopy. Our findings show that increasing electrolyte concentration decreases the number of free CH<sub>3</sub>CN molecules, significantly altering solvation structures at the electrode surface. Decomposed CH<sub>3</sub>CN species predominate the gold electrode surface, while the irreversible side reactions are suppressed in highly concentrated electrolytes. This research highlights the importance of electrolyte concentration in optimizing solvation structures and enhancing the electrolyte stability of Li–O<sub>2</sub> batteries.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"98 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1021/acs.jpcc.4c04866
Sara Fazeli, Pascal Brault, Amaël Caillard, Eric Millon
Describing the activation of O2 on metal surfaces is crucial for understanding fundamental electrochemical processes, such as the oxygen reduction reaction (ORR) in hydrogen fuel cells. This study explores how defects influence O2 adsorption mechanisms on a zirconia-based cathode. In the first step, we model O2 adsorption on two defective surfaces: oxygen-deficient t-ZrO2–x and oxynitride t-ZrO2–xNx, in an aqueous solution. We describe various O2 adsorption states by analyzing charge transfer and cohesive energy changes in O2 molecules, Zr active sites, and defects. The results suggest that O2 adsorption mechanisms on the surfaces of t-ZrO2–x and t-ZrO2–xNx occur through dissociative and associative pathways, respectively. Additionally, O2 adsorption on t-ZrO2–xNx leads to the departure of N dopants from the surface, which is unfavorable for catalytic activity. In the second step, we modified the surfaces of t-ZrO2–x and t-ZrO2–xNx with the hydroxyl (OH) group. Afterward, we simulate the O2 activation process on these modified surfaces and identify the most probable active sites. Our findings reveal that OH groups stabilize N dopants on hydroxylated t-ZrO2–xNx, preventing their loss. Moreover, OH groups influence the O2 adsorption mechanism on t-ZrO2–x, shifting toward associative O–O bond breaking. Conversely, O2 adsorption on hydroxylated t-ZrO2–xNx remains molecularly associative. Overall, on hydroxylated surfaces, O2 adsorption involves stronger charge transfer among oxygen, defects, and Zr active sites. In the third step, we explored the trends of desorption of the O2 from these surfaces. This entails analyzing O2 desorption using steered molecular dynamics (SMD) to generate potential mean force (PMF) profiles and applying Jarzynski’s equality to calculate the free energy of desorption. Herein, we find that the free energy of the desorption of O2 from hydroxylated surfaces is lower, indicating a more spontaneous process compared to t-ZrO2–x and t-ZrO2–xNx. Moreover, we discover that oxygen has the highest tendency to desorb from the hydroxylated-ZrO2–x surface, which is attributed to the lowest free energy involved in pulling oxygen from the surface, potentially influencing ORR acceleration. These findings offer valuable guidance for developing efficient nonplatinum-based cathode materials, particularly in catalysis applications.
{"title":"Hydroxyl-Induced Modification of Oxygen Activation and Desorption Free Energy on Defective Tetragonal Zirconia Catalysts","authors":"Sara Fazeli, Pascal Brault, Amaël Caillard, Eric Millon","doi":"10.1021/acs.jpcc.4c04866","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c04866","url":null,"abstract":"Describing the activation of O<sub>2</sub> on metal surfaces is crucial for understanding fundamental electrochemical processes, such as the oxygen reduction reaction (ORR) in hydrogen fuel cells. This study explores how defects influence O<sub>2</sub> adsorption mechanisms on a zirconia-based cathode. In the first step, we model O<sub>2</sub> adsorption on two defective surfaces: oxygen-deficient t-ZrO<sub>2–<i>x</i></sub> and oxynitride t-ZrO<sub>2–<i>x</i></sub>N<sub><i>x</i></sub>, in an aqueous solution. We describe various O<sub>2</sub> adsorption states by analyzing charge transfer and cohesive energy changes in O<sub>2</sub> molecules, Zr active sites, and defects. The results suggest that O<sub>2</sub> adsorption mechanisms on the surfaces of t-ZrO<sub>2–<i>x</i></sub> and t-ZrO<sub>2–<i>x</i></sub>N<sub><i>x</i></sub> occur through dissociative and associative pathways, respectively. Additionally, O<sub>2</sub> adsorption on t-ZrO<sub>2–<i>x</i></sub>N<sub><i>x</i></sub> leads to the departure of N dopants from the surface, which is unfavorable for catalytic activity. In the second step, we modified the surfaces of t-ZrO<sub>2–<i>x</i></sub> and t-ZrO<sub>2–<i>x</i></sub>N<sub><i>x</i></sub> with the hydroxyl (OH) group. Afterward, we simulate the O<sub>2</sub> activation process on these modified surfaces and identify the most probable active sites. Our findings reveal that OH groups stabilize N dopants on hydroxylated t-ZrO<sub>2–<i>x</i></sub>N<sub><i>x</i></sub>, preventing their loss. Moreover, OH groups influence the O<sub>2</sub> adsorption mechanism on t-ZrO<sub>2–<i>x</i></sub>, shifting toward associative O–O bond breaking. Conversely, O<sub>2</sub> adsorption on hydroxylated t-ZrO<sub>2–<i>x</i></sub>N<sub><i>x</i></sub> remains molecularly associative. Overall, on hydroxylated surfaces, O<sub>2</sub> adsorption involves stronger charge transfer among oxygen, defects, and Zr active sites. In the third step, we explored the trends of desorption of the O<sub>2</sub> from these surfaces. This entails analyzing O<sub>2</sub> desorption using steered molecular dynamics (SMD) to generate potential mean force (PMF) profiles and applying Jarzynski’s equality to calculate the free energy of desorption. Herein, we find that the free energy of the desorption of O<sub>2</sub> from hydroxylated surfaces is lower, indicating a more spontaneous process compared to t-ZrO<sub>2–<i>x</i></sub> and t-ZrO<sub>2–<i>x</i></sub>N<sub><i>x</i></sub>. Moreover, we discover that oxygen has the highest tendency to desorb from the hydroxylated-ZrO<sub>2–<i>x</i></sub> surface, which is attributed to the lowest free energy involved in pulling oxygen from the surface, potentially influencing ORR acceleration. These findings offer valuable guidance for developing efficient nonplatinum-based cathode materials, particularly in catalysis applications.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"8 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Near-infrared nanophosphors have attracted attention due to their wide application fields, including component analysis, bioimaging, and spectral converters of sunlight for crystalline silicon solar cells (c-Si). Yb3+ ions exhibit near-infrared (NIR) luminescence at around 1000 nm, which is consistent with the first biological window and the maximum responsivity range of c-Si. Therefore, we focused on and successfully synthesized Bi3+/Yb3+-doped NIR luminescence nanophosphors, RE2MoO6:Bi3+,Yb3+ (RE=Gd, Y, and Lu) and Gd2Mo1–xWxO6:Bi3+,Yb3+ (x = 0–0.5), utilizing a solvothermal reaction process. All samples exhibit NIR luminescence of Yb3+ ions under ultra-violet (UV) light excitation and broadband excitation due to the charge transfer transition between the O 2p/Bi 6s and Mo 4d or W 5d orbitals, indicated by their optical properties of photoluminescence (PL), PL excitation (PLE), and reflectance spectra. Furthermore, to evaluate the contribution of the Gd2MoO6:Bi,Yb (GMO:Bi,Yb) nanophosphor to the conversion efficiency of c-Si, a phosphor-converted film was made using dimethylpolysiloxane (PDMS) and the GMO:Bi,Yb nanophosphor. The results showed that the conversion efficiency of c-Si with the PDMS/GMO:Bi,Yb film is higher than that of c-Si with the PDMS-only film. Based on these results, the utilization of down-shifting nanophosphors is able to enhance the conversion efficiency of c-Si, which could be beneficial in addressing future energy challenges.
{"title":"Luminescence Tuning of NIR Luminescence Nanophosphor Bi3+/Yb3+-Doped RE2MoO6 (RE = Gd, Y, and Lu) and Gd2Mo1–xWxO6","authors":"Taisei Hangai, Takuya Hasegawa, Jian Xu, Takayuki Nakanishi, Takashi Takeda, Tomoyo Goto, Yasushi Sato, Ayahisa Okawa, Shu Yin","doi":"10.1021/acs.jpcc.4c04814","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c04814","url":null,"abstract":"Near-infrared nanophosphors have attracted attention due to their wide application fields, including component analysis, bioimaging, and spectral converters of sunlight for crystalline silicon solar cells (c-Si). Yb<sup>3+</sup> ions exhibit near-infrared (NIR) luminescence at around 1000 nm, which is consistent with the first biological window and the maximum responsivity range of c-Si. Therefore, we focused on and successfully synthesized Bi<sup>3+</sup>/Yb<sup>3+</sup>-doped NIR luminescence nanophosphors, RE<sub>2</sub>MoO<sub>6</sub>:Bi<sup>3+</sup>,Yb<sup>3+</sup> (RE=Gd, Y, and Lu) and Gd<sub>2</sub>Mo<sub>1–<i>x</i></sub>W<sub><i>x</i></sub>O<sub>6</sub>:Bi<sup>3+</sup>,Yb<sup>3+</sup> (<i>x</i> = 0–0.5), utilizing a solvothermal reaction process. All samples exhibit NIR luminescence of Yb<sup>3+</sup> ions under ultra-violet (UV) light excitation and broadband excitation due to the charge transfer transition between the O 2p/Bi 6s and Mo 4d or W 5d orbitals, indicated by their optical properties of photoluminescence (PL), PL excitation (PLE), and reflectance spectra. Furthermore, to evaluate the contribution of the Gd<sub>2</sub>MoO<sub>6</sub>:Bi,Yb (GMO:Bi,Yb) nanophosphor to the conversion efficiency of c-Si, a phosphor-converted film was made using dimethylpolysiloxane (PDMS) and the GMO:Bi,Yb nanophosphor. The results showed that the conversion efficiency of c-Si with the PDMS/GMO:Bi,Yb film is higher than that of c-Si with the PDMS-only film. Based on these results, the utilization of down-shifting nanophosphors is able to enhance the conversion efficiency of c-Si, which could be beneficial in addressing future energy challenges.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"71 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1021/acs.jpcc.4c06610
Zexun Cui, Pingping Zhang, Weixin Li, Pengyu Zhou, Yu Zhang, Bao Liu, Yuqiang Li
All-inorganic perovskite CsPbX3 (X = Cl, Br, or I) and related materials have shown great potential for applications in solar cells, light-emitting diodes, and photodetectors. A kind of heterostructure was proposed comprising CsPbBr3/ZnS nanocrystals in order to enhance the luminescence properties of CsPbBr3 nanocrystals. The incorporation of ZnS induces recombination at the interface, facilitating charge transfer and the formation of a type-II heterostructure. The luminescence characteristics of this heterostructure can be modulated by applying pressure. The photoluminescence intensity of the CsPbBr3/ZnS nanocrystals is significantly enhanced up to 0.29 GPa. With further pressure increase, these nanocrystals exhibit a red shift in emission wavelength, resulting in a high sensitivity (dλ/dP) of 9.59 nm GPa–1 and an absolute sensitivity (dFWHM/dP) of 6.07 nm GPa–1. Photoluminescence quenching occurs until the completely undetectable emission at a pressure of 2.38 GPa. The observed anomalous enhancement and wavelength red shift indicate that pressure can promote the transition from free excitons to self-trapping excitons, leading to energy transfer between ZnS and CsPbBr3. This study enhances the understanding effect of high pressure on luminescent materials in heterostructures.
{"title":"Pressure Effect on Luminescence Characteristics and Energy Transfer in CsPbBr3/ZnS Nanocrystal Heterostructures","authors":"Zexun Cui, Pingping Zhang, Weixin Li, Pengyu Zhou, Yu Zhang, Bao Liu, Yuqiang Li","doi":"10.1021/acs.jpcc.4c06610","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c06610","url":null,"abstract":"All-inorganic perovskite CsPbX<sub>3</sub> (X = Cl, Br, or I) and related materials have shown great potential for applications in solar cells, light-emitting diodes, and photodetectors. A kind of heterostructure was proposed comprising CsPbBr<sub>3</sub>/ZnS nanocrystals in order to enhance the luminescence properties of CsPbBr<sub>3</sub> nanocrystals. The incorporation of ZnS induces recombination at the interface, facilitating charge transfer and the formation of a type-II heterostructure. The luminescence characteristics of this heterostructure can be modulated by applying pressure. The photoluminescence intensity of the CsPbBr<sub>3</sub>/ZnS nanocrystals is significantly enhanced up to 0.29 GPa. With further pressure increase, these nanocrystals exhibit a red shift in emission wavelength, resulting in a high sensitivity (dλ/d<i>P</i>) of 9.59 nm GPa<sup>–1</sup> and an absolute sensitivity (dFWHM/d<i>P</i>) of 6.07 nm GPa<sup>–1</sup>. Photoluminescence quenching occurs until the completely undetectable emission at a pressure of 2.38 GPa. The observed anomalous enhancement and wavelength red shift indicate that pressure can promote the transition from free excitons to self-trapping excitons, leading to energy transfer between ZnS and CsPbBr<sub>3</sub>. This study enhances the understanding effect of high pressure on luminescent materials in heterostructures.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"21 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1021/acs.jpcc.4c05559
Michael Häfner, Matteo Bianchini
NaAlCl4 is an established solid electrolyte in high-temperature Na-based battery systems, but its ionic conductivity is not sufficiently high for room-temperature applications. We employ density functional theory and thermodynamic corrections to evaluate the efficacy of various elements for substitution, utilizing on-the-fly machine-learned potentials to accelerate the required phonon calculations by 1 order of magnitude at a minor error of −0.7 ± 1.0 meV/atom. All investigated isovalent substitutions are favorable within 4 meV/atom, with potassium and silver as substitutes for sodium and gallium as a substitute for aluminum. The most promising aliovalent substitution was identified for Zn on the tieline between NaAlCl4 and Na2ZnCl4. The structure of latter, with aluminum ions replacing zinc, yields a structure with separate layers for the differently charged cations and vacancies for potential Na conduction. Our investigation may pave the way for more reliable discovery of new Na conductors by inclusion of thermodynamic properties.
NaAlCl4 是高温钠基电池系统中一种成熟的固体电解质，但其离子电导率在室温应用中不够高。我们采用密度泛函理论和热力学修正来评估各种元素的替代功效，利用即时机器学习的电势将所需的声子计算速度提高了 1 个数量级，微小误差为 -0.7 ± 1.0 meV/原子。所研究的所有异价置换在 4 meV/原子内都是有利的，钾和银可替代钠，镓可替代铝。在 NaAlCl4 和 Na2ZnCl4 之间的铁线上发现了最有希望的锌的别价取代。后者的结构中，铝离子取代了锌，从而产生了一种结构，其中不同电荷的阳离子有不同的层，而空位则可用于潜在的 Na 传导。我们的研究可通过纳入热力学性质，为更可靠地发现新的 Na 导体铺平道路。
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Pub Date : 2024-11-15DOI: 10.1021/acs.jpcc.4c07213
Anna Zhukova, Yuri Fionov, Sophya Semenova, Seraphim Khaibullin, Sofia Chuklina, Konstantin Maslakov, Dmitry Zhukov, Oksana Isaikina, Anton Mushtakov, Alexander Fionov
Development of stable Ni-based catalysts with high resistance to sintering and carbon deposition is a challenge in the catalytic ethanol dry reforming (EDR) process. An effective and practical strategy is to introduce a second metal to obtain Ni-based bimetallic catalysts. In this study, bimetallic Cu–Ni nanoparticles supported on Al–Zr–Ce (ACZ) complex oxides were successfully developed as a multifunctional catalyst for syngas production via EDR and were compared with monometallic Ni and Cu catalysts supported on ACZ oxides. The addition of a small amount of copper (1%) to the catalyst resulted in the formation of a Cu–Ni alloy with crystallite sizes ranging from 10 to 30 nm, exhibiting a high metal–support interaction and resistance to sintering. However, a high Cu content limited the activity of the catalysts due to side reactions of ethanol decomposition, which led to catalyst deactivation. The catalyst 1Cu–9Ni/50ACZ exhibited the highest H2 and CO yields (78% and 70%, respectively, at T = 750 °C) at H2/CO = 1.1. The addition of Cu enhanced the H2/CO ratio by shifting the water–gas shift (WGS) reaction pathway and increasing the reducibility and dispersibility of Ni, which is attributed to the formation of a Cu–Ni alloy. The Cu–Ni alloy is active in the WGS reaction and has a synergistic effect with Ni in dehydration and dehydrogenation of ethanol, which affects the product distribution. Furthermore, copper plays a role in the reduction of carbide forms of nickel, which are precursors of graphitized coke. The support composition was also found to have a significant effect on the activity and stability of the bimetallic catalysts. It was demonstrated that the Al/Zr ratio in the support enables tuning the crystallite size of the active phase, which affects the surface concentrations of nickel and copper and their ratio and determines the ratio of reactive oxygen species that contribute to the gasification of the formed coke. This work provides a strategy to design highly selective catalysts with functional metal sites for hydrogen or syngas production with a regulated H2/CO ratio.
{"title":"Ethanol Dry Reforming for Hydrogen-Rich Syngas Production over Cu-Promoted Ni/Al2O3–ZrO2 Catalysts","authors":"Anna Zhukova, Yuri Fionov, Sophya Semenova, Seraphim Khaibullin, Sofia Chuklina, Konstantin Maslakov, Dmitry Zhukov, Oksana Isaikina, Anton Mushtakov, Alexander Fionov","doi":"10.1021/acs.jpcc.4c07213","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c07213","url":null,"abstract":"Development of stable Ni-based catalysts with high resistance to sintering and carbon deposition is a challenge in the catalytic ethanol dry reforming (EDR) process. An effective and practical strategy is to introduce a second metal to obtain Ni-based bimetallic catalysts. In this study, bimetallic Cu–Ni nanoparticles supported on Al–Zr–Ce (ACZ) complex oxides were successfully developed as a multifunctional catalyst for syngas production via EDR and were compared with monometallic Ni and Cu catalysts supported on ACZ oxides. The addition of a small amount of copper (1%) to the catalyst resulted in the formation of a Cu–Ni alloy with crystallite sizes ranging from 10 to 30 nm, exhibiting a high metal–support interaction and resistance to sintering. However, a high Cu content limited the activity of the catalysts due to side reactions of ethanol decomposition, which led to catalyst deactivation. The catalyst 1Cu–9Ni/50ACZ exhibited the highest H<sub>2</sub> and CO yields (78% and 70%, respectively, at <i>T</i> = 750 °C) at H<sub>2</sub>/CO = 1.1. The addition of Cu enhanced the H<sub>2</sub>/CO ratio by shifting the water–gas shift (WGS) reaction pathway and increasing the reducibility and dispersibility of Ni, which is attributed to the formation of a Cu–Ni alloy. The Cu–Ni alloy is active in the WGS reaction and has a synergistic effect with Ni in dehydration and dehydrogenation of ethanol, which affects the product distribution. Furthermore, copper plays a role in the reduction of carbide forms of nickel, which are precursors of graphitized coke. The support composition was also found to have a significant effect on the activity and stability of the bimetallic catalysts. It was demonstrated that the Al/Zr ratio in the support enables tuning the crystallite size of the active phase, which affects the surface concentrations of nickel and copper and their ratio and determines the ratio of reactive oxygen species that contribute to the gasification of the formed coke. This work provides a strategy to design highly selective catalysts with functional metal sites for hydrogen or syngas production with a regulated H<sub>2</sub>/CO ratio.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"75 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142642728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Fe–Ni Invar alloy is extensively utilized in industry due to its nearly zero thermal expansion coefficient at room temperature. Concurrently, the origin of the Invar effect has been a subject of continuous investigation for over a century. There is currently increasing interest in the connection between noncollinear magnetism and the Invar effect, but the underlying physical mechanism remains unclear. In this work, systematic DFT+U calculations confirm that the spontaneous magnetostriction of Invar alloy can be well evaluated with a suitable Hubbard U correction. Constrained DFT combined with atomic spin dynamics is employed to verify the longitudinal spin attenuation behavior (i.e., the reduction of moment magnitude) induced by the magnetic disorder in the noncollinear magnetic structure model. These extraordinary phenomena related to the Invar effect can be attributed to the transition mechanism of atomic bonding characteristics, primarily manifested by the transformation of the localized antibonding states to the nonbonding states in the Fe atom pairs by crystal orbital Hamilton population analysis. Furthermore, the electronic structure calculations indicate that with the enhancement of noncollinear orientation disorder, there is electron transfer from antibonding states to nonbonding states near the Fermi level. The bonding transition mechanism provides a simple and effective pattern for understanding the Invar effect.
铁-镍因瓦合金在室温下的热膨胀系数几乎为零，因此被广泛应用于工业领域。与此同时，一个多世纪以来，人们一直在研究因瓦效应的起源。目前，人们对非共轭磁性与因瓦效应之间的联系越来越感兴趣，但其基本物理机制仍不清楚。在这项工作中，系统的 DFT+U 计算证实，通过适当的 Hubbard U 修正，可以很好地评估因瓦合金的自发磁致伸缩。约束 DFT 与原子自旋动力学相结合，验证了非共轭磁结构模型中磁性无序引起的纵向自旋衰减行为（即磁矩大小的减小）。这些与因瓦效应相关的非凡现象可归因于原子成键特性的转变机制，通过晶体轨道汉密尔顿种群分析，主要表现为铁原子对中局部反键态向非键态的转变。此外，电子结构计算表明，随着非共线取向无序性的增强，费米水平附近存在着从反键态向非键态的电子转移。成键转变机制为理解因瓦效应提供了一个简单而有效的模式。
{"title":"Bonding Transition Mechanism in Invar Alloy Induced by Noncollinear Magnetic Disorder: DFT+U Insights","authors":"Jian Huang, Junnan Guo, Qingshui Liu, Wenhui Fang, Mengshuang Fu, Yanyan Jiang, Weikang Wu, Hui Li","doi":"10.1021/acs.jpcc.4c05726","DOIUrl":"https://doi.org/10.1021/acs.jpcc.4c05726","url":null,"abstract":"The Fe–Ni Invar alloy is extensively utilized in industry due to its nearly zero thermal expansion coefficient at room temperature. Concurrently, the origin of the Invar effect has been a subject of continuous investigation for over a century. There is currently increasing interest in the connection between noncollinear magnetism and the Invar effect, but the underlying physical mechanism remains unclear. In this work, systematic DFT+<i>U</i> calculations confirm that the spontaneous magnetostriction of Invar alloy can be well evaluated with a suitable Hubbard <i>U</i> correction. Constrained DFT combined with atomic spin dynamics is employed to verify the longitudinal spin attenuation behavior (i.e., the reduction of moment magnitude) induced by the magnetic disorder in the noncollinear magnetic structure model. These extraordinary phenomena related to the Invar effect can be attributed to the transition mechanism of atomic bonding characteristics, primarily manifested by the transformation of the localized antibonding states to the nonbonding states in the Fe atom pairs by crystal orbital Hamilton population analysis. Furthermore, the electronic structure calculations indicate that with the enhancement of noncollinear orientation disorder, there is electron transfer from antibonding states to nonbonding states near the Fermi level. The bonding transition mechanism provides a simple and effective pattern for understanding the Invar effect.","PeriodicalId":61,"journal":{"name":"The Journal of Physical Chemistry C","volume":"45 1","pages":""},"PeriodicalIF":4.126,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142637565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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