Pub Date : 2025-01-18DOI: 10.1021/acs.jpclett.4c03301
Shuhua Wang, Baibiao Huang, Ying Dai, Wei Wei
Electrochemical nitrogen conversion for ammonia (NH3) synthesis, driven by renewable electricity, offers a sustainable alternative to the traditional Haber–Bosch process. However, this conversion process remains limited by a low Faradaic efficiency (FE) and NH3 yield. Although transition metals have been widely studied as catalysts for NH3 synthesis through effective electron donation/back-donation mechanisms, there are challenges in electrochemical environments, including competitive hydrogen evolution reaction (HER) and catalyst stability issues. In contrast, p-block elements show unique advantages in light of higher selectivity for nitrogen activation and chemical stability. The present article explores the potential of p-block element-based catalysts as active sites for NH3 synthesis, discussing their activation mechanisms, performance modulation strategies, and future research directions from a theoretical perspective.
{"title":"Electrochemical Ammonia Synthesis at p-Block Active Sites Using Various Nitrogen Sources: Theoretical Insights","authors":"Shuhua Wang, Baibiao Huang, Ying Dai, Wei Wei","doi":"10.1021/acs.jpclett.4c03301","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03301","url":null,"abstract":"Electrochemical nitrogen conversion for ammonia (NH<sub>3</sub>) synthesis, driven by renewable electricity, offers a sustainable alternative to the traditional Haber–Bosch process. However, this conversion process remains limited by a low Faradaic efficiency (FE) and NH<sub>3</sub> yield. Although transition metals have been widely studied as catalysts for NH<sub>3</sub> synthesis through effective electron donation/back-donation mechanisms, there are challenges in electrochemical environments, including competitive hydrogen evolution reaction (HER) and catalyst stability issues. In contrast, <i>p</i>-block elements show unique advantages in light of higher selectivity for nitrogen activation and chemical stability. The present article explores the potential of <i>p</i>-block element-based catalysts as active sites for NH<sub>3</sub> synthesis, discussing their activation mechanisms, performance modulation strategies, and future research directions from a theoretical perspective.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"31 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-18DOI: 10.1021/acs.jpclett.4c03220
Erica Britt, Hugo A. López Peña, Jacob M. Shusterman, Kunjal Sangroula, Ka Un Lao, Katharine Moore Tibbetts
Ethylene glycol dinitrate (EGDN) is a nitrate ester explosive widely used in military ordnance and missile systems. This study investigates the decomposition dynamics of the EGDN cation using a comprehensive approach that combines femtosecond time-resolved mass spectrometry (FTRMS) experiments with ab initio electronic structure and molecular dynamics computations. We identify three distinct dissociation time scales for the metastable EGDN cation of approximately 40–60 fs, 340–450 fs, and >2 ps. The observed dissociation time scales are rationalized by electronic and geometric relaxation of multiple EGDN conformers. These insights are crucial for advancing knowledge of the initial molecular decomposition processes that are central to the detonation physics of nitrate esters, which can lead to improving safety protocols and optimizing the performance of nitrate ester explosives in various applications.
{"title":"Ultrafast Dissociation Dynamics of the Sensitive Explosive Ethylene Glycol Dinitrate","authors":"Erica Britt, Hugo A. López Peña, Jacob M. Shusterman, Kunjal Sangroula, Ka Un Lao, Katharine Moore Tibbetts","doi":"10.1021/acs.jpclett.4c03220","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03220","url":null,"abstract":"Ethylene glycol dinitrate (EGDN) is a nitrate ester explosive widely used in military ordnance and missile systems. This study investigates the decomposition dynamics of the EGDN cation using a comprehensive approach that combines femtosecond time-resolved mass spectrometry (FTRMS) experiments with <i>ab initio</i> electronic structure and molecular dynamics computations. We identify three distinct dissociation time scales for the metastable EGDN cation of approximately 40–60 fs, 340–450 fs, and >2 ps. The observed dissociation time scales are rationalized by electronic and geometric relaxation of multiple EGDN conformers. These insights are crucial for advancing knowledge of the initial molecular decomposition processes that are central to the detonation physics of nitrate esters, which can lead to improving safety protocols and optimizing the performance of nitrate ester explosives in various applications.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"101 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Herein, a simple ambient conditioned sunlight promoted photochemical reduction reaction is demonstrated for the of nitrate (NO3–) conversion to ammonia (NH3) with the maximum conversion yield of ∼16 mM using iron filings (f-Fe) in the presence of H2O2. Based on a radical scavenging study of reactive species and the characterization of catalyst f-Fe before and after the reaction, a plausible mechanism has been proposed for the ambient conditioned synthesis of NH3. The results associated with the NH3 synthesis have been verified using the 15N isotopic labeled nitrate (15NO3–), which supports the simpler viability of the reported procedure.
{"title":"H2O2 Mediated Photoreduction of Nitrates to Ammonia by Iron Filings under Ambient Conditions","authors":"Anjali Kumari Garg, Vishrant Kumar, Rohit, Deepika Saini, Sumit Kumar Sonkar","doi":"10.1021/acs.jpclett.4c03039","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03039","url":null,"abstract":"Herein, a simple ambient conditioned sunlight promoted photochemical reduction reaction is demonstrated for the of nitrate (NO<sub>3</sub><sup>–</sup>) conversion to ammonia (NH<sub>3</sub>) with the maximum conversion yield of ∼16 mM using iron filings (f-Fe) in the presence of H<sub>2</sub>O<sub>2</sub>. Based on a radical scavenging study of reactive species and the characterization of catalyst f-Fe before and after the reaction, a plausible mechanism has been proposed for the ambient conditioned synthesis of NH<sub>3</sub>. The results associated with the NH<sub>3</sub> synthesis have been verified using the <sup>15</sup>N isotopic labeled nitrate (<sup>15</sup>NO<sub>3</sub><sup>–</sup>), which supports the simpler viability of the reported procedure.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"37 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite being studied for almost two centuries, aromaticity has always been a controversial concept. We previously proposed a unified aromatic rule for π-conjugated systems by two-dimensional (2D) superatomic-molecule theory, where benzenoid rings are treated as period 2 2D superatoms (3π-◊N, 4π-◊O, 5π-◊F, 6π-◊Ne) and, further, bond to form 2D superatomic molecules. Herein, to build a 2D periodic table, we further extend the theory to period 3 (7π-◊P, 8π-◊S, 9π-◊Cl, 10π-◊Ar) and period 1 (1π-◊H, 2π-◊He) elements. Various polycyclic π-conjugated species, namely, C18H16, C14H12, C18H14, [C21H15]−, and C2B4H4, are treated as ◊Cl2, ◊Cl◊F, ◊S◊F2, ◊P◊F3, and ◊H2 superatomic molecules, respectively, where each 2D superatom achieves π electronic shell-closure via superatomic lone pairs and/or two supercenter-two electron (2sc-2e) bonds. Due to the special π electron arrangement and small superatomic orbital energy gaps, period 3 superatoms engage in novel DD, PD orbital interactions and PD, SD2 hybridizations. This work replenishes the 2D periodic table and their bonding rules.
{"title":"Bonding Features of Period 3 and Period 1 Two-Dimensional Superatoms","authors":"Mengxuan Ling, Yuanyuan Zheng, Xinlei Yu, Qinqin Yuan, Dan Li, Longjiu Cheng","doi":"10.1021/acs.jpclett.4c03492","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03492","url":null,"abstract":"Despite being studied for almost two centuries, aromaticity has always been a controversial concept. We previously proposed a unified aromatic rule for π-conjugated systems by two-dimensional (2D) superatomic-molecule theory, where benzenoid rings are treated as period 2 2D superatoms (3π-<sup>◊</sup>N, 4π-<sup>◊</sup>O, 5π-<sup>◊</sup>F, 6π-<sup>◊</sup>Ne) and, further, bond to form 2D superatomic molecules. Herein, to build a 2D periodic table, we further extend the theory to period 3 (7π-<sup>◊</sup>P, 8π-<sup>◊</sup>S, 9π-<sup>◊</sup>Cl, 10π-<sup>◊</sup>Ar) and period 1 (1π-<sup>◊</sup>H, 2π-<sup>◊</sup>He) elements. Various polycyclic π-conjugated species, namely, C<sub>18</sub>H<sub>16</sub>, C<sub>14</sub>H<sub>12</sub>, C<sub>18</sub>H<sub>14</sub>, [C<sub>21</sub>H<sub>15</sub>]<sup>−</sup>, and C<sub>2</sub>B<sub>4</sub>H<sub>4</sub>, are treated as <sup>◊</sup>Cl<sub>2</sub>, <sup>◊</sup>Cl<sup>◊</sup>F, <sup>◊</sup>S<sup>◊</sup>F<sub>2</sub>, <sup>◊</sup>P<sup>◊</sup>F<sub>3</sub>, and <sup>◊</sup>H<sub>2</sub> superatomic molecules, respectively, where each 2D superatom achieves π electronic shell-closure via superatomic lone pairs and/or two supercenter-two electron (2sc-2e) bonds. Due to the special π electron arrangement and small superatomic orbital energy gaps, period 3 superatoms engage in novel DD, PD orbital interactions and PD, SD<sup>2</sup> hybridizations. This work replenishes the 2D periodic table and their bonding rules.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"4 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142989419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1021/acs.jpclett.4c03213
Radek Crha, Peter Poliak, Michael Gillhofer, Chris Oostenbrink
In the past decade, machine-learned potentials (MLP) have demonstrated the capability to predict various QM properties learned from a set of reference QM calculations. Accordingly, hybrid QM/MM simulations can be accelerated by replacement of expensive QM calculations with efficient MLP energy predictions. At the same time, alchemical free-energy perturbations (FEP) remain unachievable at the QM level of theory. In this work, we extend the capabilities of the Buffer Region Neural Network (BuRNN) QM/MM scheme toward FEP. BuRNN introduces a buffer region that experiences full electronic polarization by the QM region to minimize artifacts at the QM/MM interface. An MLP is used to predict the energies for the QM region and its interactions with the buffer region. Furthermore, BuRNN allows us to implement FEP directly into the MLP Hamiltonian. Here, we describe the alchemical change from methanol to methane in water at the MLP/MM level as a proof of concept.
{"title":"Alchemical Free-Energy Calculations at Quantum-Chemical Precision","authors":"Radek Crha, Peter Poliak, Michael Gillhofer, Chris Oostenbrink","doi":"10.1021/acs.jpclett.4c03213","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03213","url":null,"abstract":"In the past decade, machine-learned potentials (MLP) have demonstrated the capability to predict various QM properties learned from a set of reference QM calculations. Accordingly, hybrid QM/MM simulations can be accelerated by replacement of expensive QM calculations with efficient MLP energy predictions. At the same time, alchemical free-energy perturbations (FEP) remain unachievable at the QM level of theory. In this work, we extend the capabilities of the Buffer Region Neural Network (BuRNN) QM/MM scheme toward FEP. BuRNN introduces a buffer region that experiences full electronic polarization by the QM region to minimize artifacts at the QM/MM interface. An MLP is used to predict the energies for the QM region and its interactions with the buffer region. Furthermore, BuRNN allows us to implement FEP directly into the MLP Hamiltonian. Here, we describe the alchemical change from methanol to methane in water at the MLP/MM level as a proof of concept.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"27 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1021/acs.jpclett.4c03019
Xiao Liu, Zeyao Han, Defei Yuan, Yong Chen, Ziqi Lu, Li Zhang, Yang Liu, Lilei Hu, Bin Sun
The performance of lead sulfide colloidal quantum dot (PbS-CQD) solar cells has long been hindered by interface defects in the transport layer. Traditionally, 1,2-ethanedithiol (EDT), used in solid-state ligand exchange, has been a common choice as the hole transport layer (HTL) in many PbS-CQD solar cells. However, the rapid reaction rate and chain length mismatch (shorter-chain EDT versus longer-chain oleic acid) during the ligand exchange process often introduce crack defects in the HTL film, resulting in an unexpected low performance. In this work, ethyl acetate (EA) was introduced into acetonitrile (ACN) solution to slow down the ligand exchange rate. With EA’s assistance, a high-quality HTL film with fewer cracks was achieved, leading to a reduced trap density from 2.26 × 1016 cm–3 to 1.85 × 1016 cm–3. Consequently, this led to an improved VOC by 27.5 mV and an increased power conversion efficiency (PCE) from 11.01% to 12.16%.
{"title":"Solvent Engineering in Ligand Exchange of the Hole Transport Layer Enables High-Performance PbS Quantum Dot Solar Cells","authors":"Xiao Liu, Zeyao Han, Defei Yuan, Yong Chen, Ziqi Lu, Li Zhang, Yang Liu, Lilei Hu, Bin Sun","doi":"10.1021/acs.jpclett.4c03019","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03019","url":null,"abstract":"The performance of lead sulfide colloidal quantum dot (PbS-CQD) solar cells has long been hindered by interface defects in the transport layer. Traditionally, 1,2-ethanedithiol (EDT), used in solid-state ligand exchange, has been a common choice as the hole transport layer (HTL) in many PbS-CQD solar cells. However, the rapid reaction rate and chain length mismatch (shorter-chain EDT versus longer-chain oleic acid) during the ligand exchange process often introduce crack defects in the HTL film, resulting in an unexpected low performance. In this work, ethyl acetate (EA) was introduced into acetonitrile (ACN) solution to slow down the ligand exchange rate. With EA’s assistance, a high-quality HTL film with fewer cracks was achieved, leading to a reduced trap density from 2.26 × 10<sup>16</sup> cm<sup>–3</sup> to 1.85 × 10<sup>16</sup> cm<sup>–3</sup>. Consequently, this led to an improved <i>V</i><sub>OC</sub> by 27.5 mV and an increased power conversion efficiency (PCE) from 11.01% to 12.16%.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"44 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two-dimensional (2D) black arsenic phosphorus (b-AsP) material has been attracting considerable attention for its extraordinary properties. However, its application in large-scale device fabrication remains challenging due to the limited scale and irregular shape. Here, we found the special effect of Te2 upon growth of b-AsP and developed a novel Te2-regulated steady growth (Te-SG) strategy to obtain high-quality b-AsP single crystal. The large-scale b-AsP single crystal sheet with its full width at half-maximum (FWHM) being ≤0.05° was achieved for the first time. The b-AsP monocrystalline film with atomic-level flat surface was further fabricated by laser, which exhibits outstanding self-powered characteristics under various light illumination, including low dark current and peak room-temperature detectivity of 8.5 × 1010 cm Hz1/2 W–1. The excellent uniformity was also revealed through a large-plane b-AsP photodetector. This work paves a new way for the application of high-performance electronics and optoelectronics based on b-AsP.
二维（2D）黑砷磷（b-AsP）材料以其优异的性能引起了人们的广泛关注。然而，由于尺寸有限和形状不规则，其在大规模器件制造中的应用仍然具有挑战性。本研究发现了Te2对b-AsP生长的特殊影响，并开发了一种新的Te2调控稳定生长（Te-SG）策略，以获得高质量的b-AsP单晶。首次获得了半最大全宽≤0.05°的大型b-AsP单晶片。利用激光进一步制备了具有原子级平面的b-AsP单晶薄膜，该薄膜在各种光照条件下具有良好的自供电特性，具有低暗电流和8.5 × 1010 cm Hz1/2 W-1的峰值室温探测率。通过大平面b-AsP光电探测器也发现了良好的均匀性。本工作为基于b-AsP的高性能电子学和光电子学的应用开辟了新的道路。
{"title":"Te2-Regulated Black Arsenic Phosphorus Monocrystalline Film with Excellent Uniformity for High Performance Photodetection","authors":"Jiaqi Song, Yanjie Liang, Fenghua Ding, Yong Ke, Yun Li, Yunyan Wang, Xiangheng Liu, Zhenxing Liu, Xinting Lai, Jia Zhou, Xiaobo Min, Liyuan Chai, Cong Peng","doi":"10.1021/acs.jpclett.4c03371","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03371","url":null,"abstract":"Two-dimensional (2D) black arsenic phosphorus (b-AsP) material has been attracting considerable attention for its extraordinary properties. However, its application in large-scale device fabrication remains challenging due to the limited scale and irregular shape. Here, we found the special effect of Te<sub>2</sub> upon growth of b-AsP and developed a novel Te<sub>2</sub>-regulated steady growth (Te-SG) strategy to obtain high-quality b-AsP single crystal. The large-scale b-AsP single crystal sheet with its full width at half-maximum (FWHM) being ≤0.05° was achieved for the first time. The b-AsP monocrystalline film with atomic-level flat surface was further fabricated by laser, which exhibits outstanding self-powered characteristics under various light illumination, including low dark current and peak room-temperature detectivity of 8.5 × 10<sup>10</sup> cm Hz<sup>1/2</sup> W<sup>–1</sup>. The excellent uniformity was also revealed through a large-plane b-AsP photodetector. This work paves a new way for the application of high-performance electronics and optoelectronics based on b-AsP.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"4 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-16DOI: 10.1021/acs.jpclett.4c02884
Haeyeon Jun, Denis Tondelier, Bernard Geffroy, Ileana Florea, Jean-Eric Bouree, Pilar Lopez-Varo, Philip Schulz, Yvan Bonnassieux, Sufal Swaraj
We study the influence of electrical biasing on the modification of the chemical composition and electrical performance of perovskite solar cells (PSCs) by coupling electrochemical impedance spectroscopy (EIS) and scanning transmission X-ray microscopy (STXM) techniques. EIS reveals the formation of charge accumulation at the interfaces and changes in the resistive and capacitive properties. STXM study on PSCs after applying a strong electric field for a long biasing time indicates the breakdown of methylammonium (MA+) cation, promoting iodide ions to migrate and create defects at the interface. This complementary EIS and STXM study allows the suggestion of a degradation mechanism that includes the migration of iodide ions that leads to interface defects and subsequent degradation of solar cell performance. In addition, we study the evolution of the performance of PSCs under air. We observe an increased hysteresis index on current–voltage curves and fill factor reduction of the perovskite solar cells with aging in air. EIS measurements show the formation of a capacitive layer resulting from the accumulation of iodide ions through modification of the mobile ion concentration and ion mobility.
我们通过电化学阻抗谱（EIS）和扫描透射 X 射线显微镜（STXM）技术，研究了电偏压对改变过氧化物太阳能电池（PSCs）化学成分和电性能的影响。EIS 揭示了界面上电荷积累的形成以及电阻和电容特性的变化。在长时间施加强电场偏压后对 PSC 进行的 STXM 研究表明，甲基铵（MA+）阳离子被击穿，促使碘离子迁移并在界面上形成缺陷。通过这项 EIS 和 STXM 互补研究，我们提出了一种降解机制，其中包括碘离子迁移导致界面缺陷，进而导致太阳能电池性能下降。此外，我们还研究了 PSC 在空气中的性能演变。我们观察到，随着在空气中老化，包晶体太阳能电池的电流-电压曲线上的滞后指数增加，填充因子降低。EIS 测量结果表明，碘离子的积累通过改变移动离子浓度和离子迁移率形成了电容层。
{"title":"Electrochemical and Spectro-Microscopic Analyses of Charge Accumulation and Ion Migration in Dry Processed Perovskite Solar Cells under Electrical Biasing","authors":"Haeyeon Jun, Denis Tondelier, Bernard Geffroy, Ileana Florea, Jean-Eric Bouree, Pilar Lopez-Varo, Philip Schulz, Yvan Bonnassieux, Sufal Swaraj","doi":"10.1021/acs.jpclett.4c02884","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c02884","url":null,"abstract":"We study the influence of electrical biasing on the modification of the chemical composition and electrical performance of perovskite solar cells (PSCs) by coupling electrochemical impedance spectroscopy (EIS) and scanning transmission X-ray microscopy (STXM) techniques. EIS reveals the formation of charge accumulation at the interfaces and changes in the resistive and capacitive properties. STXM study on PSCs after applying a strong electric field for a long biasing time indicates the breakdown of methylammonium (MA<sup>+</sup>) cation, promoting iodide ions to migrate and create defects at the interface. This complementary EIS and STXM study allows the suggestion of a degradation mechanism that includes the migration of iodide ions that leads to interface defects and subsequent degradation of solar cell performance. In addition, we study the evolution of the performance of PSCs under air. We observe an increased hysteresis index on current–voltage curves and fill factor reduction of the perovskite solar cells with aging in air. EIS measurements show the formation of a capacitive layer resulting from the accumulation of iodide ions through modification of the mobile ion concentration and ion mobility.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"24 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-16DOI: 10.1021/acs.jpclett.4c03252
Kit Joll, Philipp Schienbein, Kevin M. Rosso, Jochen Blumberger
Atomic-scale understanding of important geochemical processes including sorption, dissolution, nucleation, and crystal growth is difficult to obtain from experimental measurements alone and would benefit from strong continuous progress in molecular simulation. To this end, we present a reactive neural network potential-based molecular dynamics approach to simulate the interaction of aqueous ions on mineral surfaces in contact with liquid water, taking Fe(II) on hematite(001) as a model system. We show that a single neural network potential predicts rate constants for water exchange for aqueous Fe(II) and for the exergonic chemisorption of aqueous Fe(II) on hematite(001) in good agreement with experimental observations. The neural network potential developed herein allows one to converge free energy profiles and transmission coefficients at density functional theory-level accuracy outperforming state-of-the-art classical force field potentials. This suggests that machine learning potential molecular dynamics should become the method of choice for atomistic studies of geochemical processes.
{"title":"Mechanism of Fe(II) Chemisorption on Hematite(001) Revealed by Reactive Neural Network Potential Molecular Dynamics","authors":"Kit Joll, Philipp Schienbein, Kevin M. Rosso, Jochen Blumberger","doi":"10.1021/acs.jpclett.4c03252","DOIUrl":"https://doi.org/10.1021/acs.jpclett.4c03252","url":null,"abstract":"Atomic-scale understanding of important geochemical processes including sorption, dissolution, nucleation, and crystal growth is difficult to obtain from experimental measurements alone and would benefit from strong continuous progress in molecular simulation. To this end, we present a reactive neural network potential-based molecular dynamics approach to simulate the interaction of aqueous ions on mineral surfaces in contact with liquid water, taking Fe(II) on hematite(001) as a model system. We show that a single neural network potential predicts rate constants for water exchange for aqueous Fe(II) and for the exergonic chemisorption of aqueous Fe(II) on hematite(001) in good agreement with experimental observations. The neural network potential developed herein allows one to converge free energy profiles and transmission coefficients at density functional theory-level accuracy outperforming state-of-the-art classical force field potentials. This suggests that machine learning potential molecular dynamics should become the method of choice for atomistic studies of geochemical processes.","PeriodicalId":62,"journal":{"name":"The Journal of Physical Chemistry Letters","volume":"41 1","pages":""},"PeriodicalIF":6.475,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142987715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-15DOI: 10.1021/acs.jpclett.4c02531
Md Ashaduzzaman, Shanlin Pan
We report a Tuning Fork Scanning Electrochemical Cell Microscopy (TF-SECCM) technique for providing morphological and electrochemical information on single redox-active entities. This new operation configuration of SECCM utilizes an electrolyte-filled nanopipette tip mounted onto a tuning fork force sensor to obtain a precise tip–sample distance control and surface morphological mapping capabilities. Redox activities of regions of interest (ROIs) can be investigated by scanning electrode potential by moving the nanopipette to any target regions while maintaining the constant force engagement of the tip with the sample. Using silver nanowires (Ag NWs) as a model system due to their extensive utilization in energy and sensing devices, TF-SECCM provides not only the topography of single Ag NWs but also their distinctive redox activities, catalytic hydrogen evolution reaction (HER) activities, and electrolyte anion adsorption/desorption features in contrast to NW bundles and a supporting substrate.
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