Hongze Gao, Da Zhou, Lu Ping, Zifan Wang, Nguyen Tuan Hung, Jun Cao, Michael Geiwitz, Gabriel Natale, Yuxuan Cosmi Lin, Kenneth Stephen Burch, Riichiro Saito, Mauricio Terrones, Xi Ling
The bulk phase of transition metal nitrides (TMNs) has long been a subject of extensive investigation due to their utility as coating materials, electrocatalysts, and diffusion barriers, attributed to their high conductivity and refractory properties. Downscaling TMNs into two-dimensional (2D) forms would provide valuable members to the existing 2D materials repertoire, with potential enhancements across various applications. Moreover, calculations have anticipated the emergence of uncommon physical phenomena in TMNs at the 2D limit. In this study, we use the atomic substitution approach to synthesize 2D W5N6 with tunable thicknesses from tens of nanometers down to 2.9 nm. The obtained flakes exhibit high crystallinity and smooth surfaces. Electrical measurements on 15 samples show an average electrical conductivity of 161.1 S/cm, which persists while thickness decreases from 45.6 to 2.9 nm. The observed weak gate-tuning effect suggests the semimetallic nature of the synthesized 2D W5N6. Further investigation of the conversion mechanism elucidates the crucial role of chalcogen vacancies in the precursor for initiating the reaction and strain in propagating the conversion. Our work introduces a desired semimetallic crystal to the 2D material library with mechanistic insights for future design of the synthesis.
{"title":"Downscaling of Non-Van der Waals Semimetallic W5N6 with Resistivity Preservation","authors":"Hongze Gao, Da Zhou, Lu Ping, Zifan Wang, Nguyen Tuan Hung, Jun Cao, Michael Geiwitz, Gabriel Natale, Yuxuan Cosmi Lin, Kenneth Stephen Burch, Riichiro Saito, Mauricio Terrones, Xi Ling","doi":"10.1021/acsnano.4c12155","DOIUrl":"https://doi.org/10.1021/acsnano.4c12155","url":null,"abstract":"The bulk phase of transition metal nitrides (TMNs) has long been a subject of extensive investigation due to their utility as coating materials, electrocatalysts, and diffusion barriers, attributed to their high conductivity and refractory properties. Downscaling TMNs into two-dimensional (2D) forms would provide valuable members to the existing 2D materials repertoire, with potential enhancements across various applications. Moreover, calculations have anticipated the emergence of uncommon physical phenomena in TMNs at the 2D limit. In this study, we use the atomic substitution approach to synthesize 2D W<sub>5</sub>N<sub>6</sub> with tunable thicknesses from tens of nanometers down to 2.9 nm. The obtained flakes exhibit high crystallinity and smooth surfaces. Electrical measurements on 15 samples show an average electrical conductivity of 161.1 S/cm, which persists while thickness decreases from 45.6 to 2.9 nm. The observed weak gate-tuning effect suggests the semimetallic nature of the synthesized 2D W<sub>5</sub>N<sub>6</sub>. Further investigation of the conversion mechanism elucidates the crucial role of chalcogen vacancies in the precursor for initiating the reaction and strain in propagating the conversion. Our work introduces a desired semimetallic crystal to the 2D material library with mechanistic insights for future design of the synthesis.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"12 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tumor-specific T cells play a vital role in potent antitumor immunity. However, their efficacy is severely affected by the spatiotemporal orchestration of antigen-presentation as well as the innate immune response in dendritic cells (DCs). Herein, we develop a minimalist nanovaccine that exploits a dual immunofunctional polymeric nanoplatform (DIPNP) to encapsulate ovalbumin (OVA) via electrostatic interaction when the nanocarrier serves as both STING agonist and immune adjuvant in DCs. In vitro results reveal that the nanocarrier induces STING activation via facilitating interferon regulatory factor 3 phosphorylation by block poly 18-crown-6-yl methacrylate (P18C6MA) mediated K+ perturbation cascade with endoplasmic reticulum stress, and stimulates DC maturation via the Toll-like receptor 4 activation by primary amine. In vivo studies indicate that the smart nanovaccine dramatically inhibits tumor growth with a long-term immune memory response in both the B16-OVA and EG7-OVA tumor models. After combination with programmed death ligand-1 antibody (aPD-L1), mice survival rate is notably prolonged. In addition, DIPNP forms a personalized nanovaccine after resected autologous primary tumor cell membranes decoration with a high antitumor activity in a homologous distant tumor model. The rational design provides inspiration for personalized nanovaccine construction via immunofunctional nanocarriers.
{"title":"Personalized Nanovaccine Based on STING-Activating Nanocarrier for Robust Cancer Immunotherapy","authors":"Yongjuan Li, Ya Dong, Danyang Shen, Yichen Guo, Yongjian Cao, Kaixin Zhang, Xinyan Li, Rongrong Zhu, Jinmeng Yi, Xiaohan Yao, Xiaowei Dang, Rui Li, Zhenzhong Zhang, Zhihai Qin, Weijing Yang","doi":"10.1021/acsnano.4c11014","DOIUrl":"https://doi.org/10.1021/acsnano.4c11014","url":null,"abstract":"Tumor-specific T cells play a vital role in potent antitumor immunity. However, their efficacy is severely affected by the spatiotemporal orchestration of antigen-presentation as well as the innate immune response in dendritic cells (DCs). Herein, we develop a minimalist nanovaccine that exploits a dual immunofunctional polymeric nanoplatform (DIPNP) to encapsulate ovalbumin (OVA) via electrostatic interaction when the nanocarrier serves as both STING agonist and immune adjuvant in DCs. In vitro results reveal that the nanocarrier induces STING activation via facilitating interferon regulatory factor 3 phosphorylation by block poly 18-crown-6-yl methacrylate (P18C6MA) mediated K<sup>+</sup> perturbation cascade with endoplasmic reticulum stress, and stimulates DC maturation via the Toll-like receptor 4 activation by primary amine. In vivo studies indicate that the smart nanovaccine dramatically inhibits tumor growth with a long-term immune memory response in both the B16-OVA and EG7-OVA tumor models. After combination with programmed death ligand-1 antibody (aPD-L1), mice survival rate is notably prolonged. In addition, DIPNP forms a personalized nanovaccine after resected autologous primary tumor cell membranes decoration with a high antitumor activity in a homologous distant tumor model. The rational design provides inspiration for personalized nanovaccine construction via immunofunctional nanocarriers.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"94 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986054","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pt-based intermetallic alloy particles with a Pt skin layer have higher catalytic activity than solid-solution alloy particles and have attracted considerable attention for practical applications in polymer electrolyte fuel cells. However, the reason for the superior performance of intermetallic alloys is not yet fully understood. Because the catalytic reaction proceeds on the topmost surface of the particle, it is necessary to clarify the relationship between the periodic structure of the intermetallic alloy and the Pt atomic coordination on the surface. This study investigated the Pt–Pt interatomic distance of a Pt skin layer formed on intermetallic Pt3Co particles at atomic resolution through precise measurements using scanning transmission electron microscopy and theoretical calculations. The Pt atomic coordination on the surface shows good agreement between experimental observations and theoretical models, although the experimental image is a projection and thus provides indirect results. The theoretical calculation model revealed that structural relaxation at the Pt and Pt3Co interfaces led to two distinct Pt bonding states at the surface, including asymmetric atomic coordination. The asymmetric coordination of the Pt site deepens the d-band center, diversifies the oxygen adsorption energies, and enhances catalytic activity. Further exploration and control of the unique surface Pt coordination environments formed on the periodic structures of intermetallic alloys should reveal promising routes for the development of catalytic particles.
{"title":"Asymmetric Atomic Coordination of Platinum Skin Layer on Intermetallic Platinum–Cobalt Particles","authors":"Shunsuke Kobayashi, Yuki Omori, Kei Nakayama, Kousuke Ooe, Hsin-Hui Huang, Akihide Kuwabara","doi":"10.1021/acsnano.4c13291","DOIUrl":"https://doi.org/10.1021/acsnano.4c13291","url":null,"abstract":"Pt-based intermetallic alloy particles with a Pt skin layer have higher catalytic activity than solid-solution alloy particles and have attracted considerable attention for practical applications in polymer electrolyte fuel cells. However, the reason for the superior performance of intermetallic alloys is not yet fully understood. Because the catalytic reaction proceeds on the topmost surface of the particle, it is necessary to clarify the relationship between the periodic structure of the intermetallic alloy and the Pt atomic coordination on the surface. This study investigated the Pt–Pt interatomic distance of a Pt skin layer formed on intermetallic Pt<sub>3</sub>Co particles at atomic resolution through precise measurements using scanning transmission electron microscopy and theoretical calculations. The Pt atomic coordination on the surface shows good agreement between experimental observations and theoretical models, although the experimental image is a projection and thus provides indirect results. The theoretical calculation model revealed that structural relaxation at the Pt and Pt<sub>3</sub>Co interfaces led to two distinct Pt bonding states at the surface, including asymmetric atomic coordination. The asymmetric coordination of the Pt site deepens the d-band center, diversifies the oxygen adsorption energies, and enhances catalytic activity. Further exploration and control of the unique surface Pt coordination environments formed on the periodic structures of intermetallic alloys should reveal promising routes for the development of catalytic particles.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"12 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhao Kang, Jiankang Lu, Shourong Zheng, Xiaojie Hu, Lianhong Wang, Lijuan Jiang, Yuqi Zheng, Lecheng Lv, Jorge L. Gardea-Torresdey, Jason C. White, Lijuan Zhao
Under a changing climate, enhancing the drought resilience of crops is critical to maintaining agricultural production and reducing food insecurity. Here, we demonstrate that seed priming with amorphous silica (SiO2) nanoparticles (NPs) (20 mg/L) accelerated seed germination speed, increased seedlings vigor, and promoted seedling growth of rice under polyethylene glycol (PEG)-mimicking drought conditions. An orthogonal approach was used to uncover the mechanisms of accelerated seed germination and enhanced drought tolerance, including electron paramagnetic resonance, Fourier transform infrared spectroscopy (FTIR), metabolomics, and transcriptomics. It was revealed that the unique surface chemistry of amorphous silica, characterized by an enrichment of silanol and siloxane groups, can catalyze the production of reactive oxygen species. This, in turn, initiates redox signaling and activates downstream drought-responsive genes. In addition, silica-primed seeds exhibited a significant enrichment of 18 amino acids and 6 sugars compared to those undergoing hydropriming, suggesting the accelerated mobilization of stored energy reserves. The drought-tolerance trait was observed in vegetative tissues of 35 day-old plants, where this tolerance was associated with an accelerated catabolism of amino acids and an enhanced anabolism of antioxidants. A separated field trial showed that SiO2NPs seed priming not only increased rice grain yield by 7.77% (p = 0.051) and 6.48% (p = 0.066), respectively, under normal and drought conditions but also increased the grain amino acid content. These results demonstrate that a simple and cost-effective nanoseed-priming approach can convey life cycle-long drought tolerance while simultaneously increasing rice grain yield and nutrition quality, providing an effective and sustainable strategy to cultivate climate-resilient crops.
{"title":"Silica-Activated Redox Signaling Confers Rice with Enhanced Drought Resilience and Grain Yield","authors":"Zhao Kang, Jiankang Lu, Shourong Zheng, Xiaojie Hu, Lianhong Wang, Lijuan Jiang, Yuqi Zheng, Lecheng Lv, Jorge L. Gardea-Torresdey, Jason C. White, Lijuan Zhao","doi":"10.1021/acsnano.4c14608","DOIUrl":"https://doi.org/10.1021/acsnano.4c14608","url":null,"abstract":"Under a changing climate, enhancing the drought resilience of crops is critical to maintaining agricultural production and reducing food insecurity. Here, we demonstrate that seed priming with amorphous silica (SiO<sub>2</sub>) nanoparticles (NPs) (20 mg/L) accelerated seed germination speed, increased seedlings vigor, and promoted seedling growth of rice under polyethylene glycol (PEG)-mimicking drought conditions. An orthogonal approach was used to uncover the mechanisms of accelerated seed germination and enhanced drought tolerance, including electron paramagnetic resonance, Fourier transform infrared spectroscopy (FTIR), metabolomics, and transcriptomics. It was revealed that the unique surface chemistry of amorphous silica, characterized by an enrichment of silanol and siloxane groups, can catalyze the production of reactive oxygen species. This, in turn, initiates redox signaling and activates downstream drought-responsive genes. In addition, silica-primed seeds exhibited a significant enrichment of 18 amino acids and 6 sugars compared to those undergoing hydropriming, suggesting the accelerated mobilization of stored energy reserves. The drought-tolerance trait was observed in vegetative tissues of 35 day-old plants, where this tolerance was associated with an accelerated catabolism of amino acids and an enhanced anabolism of antioxidants. A separated field trial showed that SiO<sub>2</sub>NPs seed priming not only increased rice grain yield by 7.77% (<i>p</i> = 0.051) and 6.48% (<i>p</i> = 0.066), respectively, under normal and drought conditions but also increased the grain amino acid content. These results demonstrate that a simple and cost-effective nanoseed-priming approach can convey life cycle-long drought tolerance while simultaneously increasing rice grain yield and nutrition quality, providing an effective and sustainable strategy to cultivate climate-resilient crops.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"83 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sameh Almousa, Susy Kim, Ashish Kumar, Yixin Su, Sangeeta Singh, Shalini Mishra, Miriam M. Fonseca, Hilal A. Rather, E. Alfonso Romero-Sandoval, Fang-Chi Hsu, Rakesh Singh, Hariom Yadav, Santosh Mishra, Gagan Deep
Gut dysbiosis contributes to multiple pathologies, yet the mechanisms of the gut microbiota-mediated influence on systemic and distant responses remain largely elusive. This study aimed to identify the role of nanosized bacterial extracellular vesicles (bEVs) in mediating allodynia, i.e., pain hypersensitivity, in a diet-induced obesity (DIO) gut dysbiosis model. bEVs were enriched from the feces of lean (bEVLean) and DIO (bEVDIO) mice by an approach combining ultracentrifugation and immunoprecipitation and then extensively analyzed for purity and bacterial characteristics. Next, bEVs were injected, either intraplantarly or intravenously, in mice to assess pain sensitivity. Fluorescence-labeled bEVs were injected in mice by enema to assess biodistribution. The effect of bEV on immune cells and inflammation was analyzed by array, immunophenotyping, microscopy, NF-κB activation, and cellular uptake assays. Results showed that bEVDIO administration in wild-type mice replicated the allodynia phenotype observed in DIO mice for both mechanical and thermal stimuli. Importantly, this effect was compromised in TRPA1/TRPV1 double-knockout mice. Biodistribution analyses showed bEV entry into systemic circulation with subsequent localization at distant sites. Multiple analyses revealed that bEVDIO exposure incited systemic inflammation, primarily through modulating the innate immune system. This inflammatory mechanism involved LPS on the bEV surface, activating TLR2- and TLR4-related pathways, as confirmed using TLR2 and TLR4 inhibitors and shaving bEV surface proteins. Interestingly, the enhanced cellular uptake of bEVDIO was contingent on interactions involving LPS and proteins on bEVs and TLR2/TLR4 on monocytes. These findings illuminate the hitherto unexplored role of bEV as pivotal mediators of allodynia and inflammation linked to gut dysbiosis.
{"title":"Bacterial Nanovesicles as Interkingdom Signaling Moieties Mediating Pain Hypersensitivity","authors":"Sameh Almousa, Susy Kim, Ashish Kumar, Yixin Su, Sangeeta Singh, Shalini Mishra, Miriam M. Fonseca, Hilal A. Rather, E. Alfonso Romero-Sandoval, Fang-Chi Hsu, Rakesh Singh, Hariom Yadav, Santosh Mishra, Gagan Deep","doi":"10.1021/acsnano.4c10529","DOIUrl":"https://doi.org/10.1021/acsnano.4c10529","url":null,"abstract":"Gut dysbiosis contributes to multiple pathologies, yet the mechanisms of the gut microbiota-mediated influence on systemic and distant responses remain largely elusive. This study aimed to identify the role of nanosized bacterial extracellular vesicles (bEVs) in mediating allodynia, i.e., pain hypersensitivity, in a diet-induced obesity (DIO) gut dysbiosis model. bEVs were enriched from the feces of lean (bEV<sup>Lean</sup>) and DIO (bEV<sup>DIO</sup>) mice by an approach combining ultracentrifugation and immunoprecipitation and then extensively analyzed for purity and bacterial characteristics. Next, bEVs were injected, either intraplantarly or intravenously, in mice to assess pain sensitivity. Fluorescence-labeled bEVs were injected in mice by enema to assess biodistribution. The effect of bEV on immune cells and inflammation was analyzed by array, immunophenotyping, microscopy, NF-κB activation, and cellular uptake assays. Results showed that bEV<sup>DIO</sup> administration in wild-type mice replicated the allodynia phenotype observed in DIO mice for both mechanical and thermal stimuli. Importantly, this effect was compromised in TRPA1/TRPV1 double-knockout mice. Biodistribution analyses showed bEV entry into systemic circulation with subsequent localization at distant sites. Multiple analyses revealed that bEV<sup>DIO</sup> exposure incited systemic inflammation, primarily through modulating the innate immune system. This inflammatory mechanism involved LPS on the bEV surface, activating TLR2- and TLR4-related pathways, as confirmed using TLR2 and TLR4 inhibitors and shaving bEV surface proteins. Interestingly, the enhanced cellular uptake of bEV<sup>DIO</sup> was contingent on interactions involving LPS and proteins on bEVs and TLR2/TLR4 on monocytes. These findings illuminate the hitherto unexplored role of bEV as pivotal mediators of allodynia and inflammation linked to gut dysbiosis.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"41 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Elham Loni, Ahmad Majed, Shengjie Zhang, Hari H. S. Thangavelu, Chaochao Dun, Anika Tabassum, Karamullah Eisawi, Jeffrey J. Urban, Per O. Å. Persson, Matthew M. Montemore, Michael Naguib
Herein, we report the synthesis of two-dimensional Ta2Se2C (2D-Ta2Se2C) nanosheets using electrochemical lithiation in multilayer Ta2Se2C followed by sonication in deionized water. Multilayer Ta2Se2C was obtained via solid-state synthesis of FexTa2Se2C followed by chemical etching of Fe. 2D-Ta2Se2C exhibited promising electrocatalytic activity for the hydrogen evolution reaction from water compared to multilayer Ta2Se2C and 2D-TaSe2. 2D-Ta2Se2C showed an overpotential at 10 mA·cm–2 (η10) of 264 mV, a Tafel slope of 91 mV·dec–1, and an electrochemically active surface area of 17.61 mECSA2·gcatalyst–1. The high performance could be attributed to the large surface area of single sheets which hence maximizes the number of exposed catalytic sites and increased density of vacancies, observed with transmission electron microscopy, during synthesis and processing.
{"title":"Two-Dimensional Tantalum Carbo-Selenide for Hydrogen Evolution","authors":"Elham Loni, Ahmad Majed, Shengjie Zhang, Hari H. S. Thangavelu, Chaochao Dun, Anika Tabassum, Karamullah Eisawi, Jeffrey J. Urban, Per O. Å. Persson, Matthew M. Montemore, Michael Naguib","doi":"10.1021/acsnano.4c09903","DOIUrl":"https://doi.org/10.1021/acsnano.4c09903","url":null,"abstract":"Herein, we report the synthesis of two-dimensional Ta<sub>2</sub>Se<sub>2</sub>C (2D-Ta<sub>2</sub>Se<sub>2</sub>C) nanosheets using electrochemical lithiation in multilayer Ta<sub>2</sub>Se<sub>2</sub>C followed by sonication in deionized water. Multilayer Ta<sub>2</sub>Se<sub>2</sub>C was obtained via solid-state synthesis of Fe<sub><i>x</i></sub>Ta<sub>2</sub>Se<sub>2</sub>C followed by chemical etching of Fe. 2D-Ta<sub>2</sub>Se<sub>2</sub>C exhibited promising electrocatalytic activity for the hydrogen evolution reaction from water compared to multilayer Ta<sub>2</sub>Se<sub>2</sub>C and 2D-TaSe<sub>2</sub>. 2D-Ta<sub>2</sub>Se<sub>2</sub>C showed an overpotential at 10 mA·cm<sup>–2</sup> (η<sub>10</sub>) of 264 mV, a Tafel slope of 91 mV·dec<sup>–1</sup>, and an electrochemically active surface area of 17.61 m<sub>ECSA</sub><sup>2</sup>·g<sub>catalyst</sub><sup>–1</sup>. The high performance could be attributed to the large surface area of single sheets which hence maximizes the number of exposed catalytic sites and increased density of vacancies, observed with transmission electron microscopy, during synthesis and processing.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"45 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Adam D. Walter, Gregory R. Schwenk, Yuanren Liu, David Bugallo Ferron, Jeffrey T. Wilk, Lucas M. Ferrer, Christopher Y. Li, Yong-Jie Hu, Michel W. Barsoum
Recently, we reported on the simple, scalable synthesis of quantum-confined one-dimensional (1D) lepidocrocite titanate nanofilaments (1DLs). Herein, we show, using solid-state UV–vis spectroscopy, that reducing the concentration of aqueous 1DL colloidal suspensions from 40 to 0.01 g/L increases the band gap energy and light absorption onset of dried filtered films from ≈3.5 to ≈4.5 eV. This range is ascribed to quantum confinement as the system transitions from two-dimensional (2D) into 1D with dilution. It is only after the colloidal suspensions are dried and the 1DLs start to self-assemble into ribbons and sheets that the band gap values change. This self-assembly is manifested in the X-ray diffraction patterns and the emergence of a Raman band characteristic of 2D lepidocrocite titanates. In colloidal form, 1DLs exhibit a lyotropic liquid crystal phase with a critical concentration of between 10 and 1 g/L. Additionally, the Beer–Lambert law applies with a mass absorbance coefficient of 2 ± 0.4 Lg–1 cm–1. The optical absorbance edges of the colloidal suspensions are not a function of concentration. The experimental findings are theoretically supported by density functional theory calculations of the Raman vibrational modes and electronic band structures of the 1D and 2D lepidocrocite titanate atomic structures.
{"title":"Concentration-Dependent Control of the Band Gap Energy of a Low-Dimensional Lepidocrocite Titanate","authors":"Adam D. Walter, Gregory R. Schwenk, Yuanren Liu, David Bugallo Ferron, Jeffrey T. Wilk, Lucas M. Ferrer, Christopher Y. Li, Yong-Jie Hu, Michel W. Barsoum","doi":"10.1021/acsnano.4c16410","DOIUrl":"https://doi.org/10.1021/acsnano.4c16410","url":null,"abstract":"Recently, we reported on the simple, scalable synthesis of quantum-confined one-dimensional (1D) lepidocrocite titanate nanofilaments (1DLs). Herein, we show, using solid-state UV–vis spectroscopy, that reducing the concentration of aqueous 1DL colloidal suspensions from 40 to 0.01 g/L increases the band gap energy and light absorption onset of dried filtered films from ≈3.5 to ≈4.5 eV. This range is ascribed to quantum confinement as the system transitions from two-dimensional (2D) into 1D with dilution. It is only after the colloidal suspensions are dried and the 1DLs start to self-assemble into ribbons and sheets that the band gap values change. This self-assembly is manifested in the X-ray diffraction patterns and the emergence of a Raman band characteristic of 2D lepidocrocite titanates. In colloidal form, 1DLs exhibit a lyotropic liquid crystal phase with a critical concentration of between 10 and 1 g/L. Additionally, the Beer–Lambert law applies with a mass absorbance coefficient of 2 ± 0.4 Lg<sup>–1</sup> cm<sup>–1</sup>. The optical absorbance edges of the colloidal suspensions are not a function of concentration. The experimental findings are theoretically supported by density functional theory calculations of the Raman vibrational modes and electronic band structures of the 1D and 2D lepidocrocite titanate atomic structures.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"8 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gaili Cao, Weinan Zhao, Lian Han, Youchao Teng, Shikuan Xu, Han Nguyen, Kam Chiu Tam
A surfactant is an efficient and common additive used to enhance the spreading of droplets on hydrophobic surfaces. However, a high surfactant concentration is required to achieve the desired performance, resulting in environmental pollution and increased costs. Additionally, the pesticide loading capacity of surfactants at low concentrations (below their critical micelle concentrations) is a concern. Thus, in this study, we developed a strategy to enhance pesticide loading and droplet deposition by mixing small amounts of sodium dodecyl sulfate (SDS) (0.1 wt %) and cationically modified cellulose nanocrystals (PCNC). The reduced surface tension, increased viscosity and adhesion, and electrostatic and hydrogen interactions resulted in a low retraction velocity, excellent spreading, and resistance to air turbulence. The improved loading content was facilitated by the hydrophobic domains of PCNC and SDS micelles.
{"title":"Enhancing Droplet Spreading on a Hydrophobic Plant Surface by Surfactant/Cellulose Nanocrystal Complexes","authors":"Gaili Cao, Weinan Zhao, Lian Han, Youchao Teng, Shikuan Xu, Han Nguyen, Kam Chiu Tam","doi":"10.1021/acsnano.4c13542","DOIUrl":"https://doi.org/10.1021/acsnano.4c13542","url":null,"abstract":"A surfactant is an efficient and common additive used to enhance the spreading of droplets on hydrophobic surfaces. However, a high surfactant concentration is required to achieve the desired performance, resulting in environmental pollution and increased costs. Additionally, the pesticide loading capacity of surfactants at low concentrations (below their critical micelle concentrations) is a concern. Thus, in this study, we developed a strategy to enhance pesticide loading and droplet deposition by mixing small amounts of sodium dodecyl sulfate (SDS) (0.1 wt %) and cationically modified cellulose nanocrystals (PCNC). The reduced surface tension, increased viscosity and adhesion, and electrostatic and hydrogen interactions resulted in a low retraction velocity, excellent spreading, and resistance to air turbulence. The improved loading content was facilitated by the hydrophobic domains of PCNC and SDS micelles.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"28 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daria D. Blach, Dana B. Sulas-Kern, Bipeng Wang, Run Long, Qiushi Ma, Oleg V. Prezhdo, Jeffrey L. Blackburn, Libai Huang
Controlling charge transport at the interfaces of nanostructures is crucial for their successful use in optoelectronic and solar energy applications. Mixed-dimensional heterostructures based on single-walled carbon nanotubes (SWCNTs) and transition metal dichalcogenides (TMDCs) have demonstrated exceptionally long-lived charge-separated states. However, the factors that control the charge transport at these interfaces remain unclear. In this study, we directly image charge transport at the interfaces of single- and multilayered MoS2 and (6,5) SWCNT heterostructures using transient absorption microscopy. We find that charge recombination becomes slower as the layer thickness of MoS2 increases. This behavior can be explained by electron delocalization in multilayers and reduced orbital overlap with the SWCNTs, as suggested by nonadiabatic (NA) molecular dynamics (MD) simulations. Dipolar repulsion of interfacial excitons results in rapid density-dependent transport within the first 100 ps. Stronger repulsion and longer-range charge transport are observed in heterostructures with thicker MoS2 layers, driven by electron delocalization and larger interfacial dipole moments. These findings are consistent with the results from NAMD simulations. Our results suggest that heterostructures with multilayer MoS2 can facilitate long-lived charge separation and transport, which is promising for applications in photovoltaics and photocatalysis.
{"title":"Long-Range Charge Transport Facilitated by Electron Delocalization in MoS2 and Carbon Nanotube Heterostructures","authors":"Daria D. Blach, Dana B. Sulas-Kern, Bipeng Wang, Run Long, Qiushi Ma, Oleg V. Prezhdo, Jeffrey L. Blackburn, Libai Huang","doi":"10.1021/acsnano.4c12858","DOIUrl":"https://doi.org/10.1021/acsnano.4c12858","url":null,"abstract":"Controlling charge transport at the interfaces of nanostructures is crucial for their successful use in optoelectronic and solar energy applications. Mixed-dimensional heterostructures based on single-walled carbon nanotubes (SWCNTs) and transition metal dichalcogenides (TMDCs) have demonstrated exceptionally long-lived charge-separated states. However, the factors that control the charge transport at these interfaces remain unclear. In this study, we directly image charge transport at the interfaces of single- and multilayered MoS<sub>2</sub> and (6,5) SWCNT heterostructures using transient absorption microscopy. We find that charge recombination becomes slower as the layer thickness of MoS<sub>2</sub> increases. This behavior can be explained by electron delocalization in multilayers and reduced orbital overlap with the SWCNTs, as suggested by nonadiabatic (NA) molecular dynamics (MD) simulations. Dipolar repulsion of interfacial excitons results in rapid density-dependent transport within the first 100 ps. Stronger repulsion and longer-range charge transport are observed in heterostructures with thicker MoS<sub>2</sub> layers, driven by electron delocalization and larger interfacial dipole moments. These findings are consistent with the results from NAMD simulations. Our results suggest that heterostructures with multilayer MoS<sub>2</sub> can facilitate long-lived charge separation and transport, which is promising for applications in photovoltaics and photocatalysis.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"3 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While thermoelectric conversion by a thermocapacitive cycle has been considered a promising green technology for low-grade heat recovery, our study finds that its practical feasibility is overestimated. During thermal charging, the coexistence and dynamic competition between thermal-induced voltage rise and self-discharge lead to the limitations of the thermocapacitive cycle. Therefore, the operational conditions in the charge-heat-discharge steps seriously restrict the thermal charging performance. The calculation of energy efficiency further confirms the economic infeasibility of the thermocapacitive cycle. This study provides insights into comprehending the principle and process of thermoelectric conversion by thermocapacitive cycle and will guide the rational development of capacitive heat-to-current converters.
{"title":"Revealing the Limitations of the Thermocapacitive Cycle","authors":"Yining Lao, Pei Tang, Jinquan Zeng, Shan Xu, Jian Zhu, Qingyun Dou, Xiaohua Xiao, Xingbin Yan","doi":"10.1021/acsnano.4c16370","DOIUrl":"https://doi.org/10.1021/acsnano.4c16370","url":null,"abstract":"While thermoelectric conversion by a thermocapacitive cycle has been considered a promising green technology for low-grade heat recovery, our study finds that its practical feasibility is overestimated. During thermal charging, the coexistence and dynamic competition between thermal-induced voltage rise and self-discharge lead to the limitations of the thermocapacitive cycle. Therefore, the operational conditions in the charge-heat-discharge steps seriously restrict the thermal charging performance. The calculation of energy efficiency further confirms the economic infeasibility of the thermocapacitive cycle. This study provides insights into comprehending the principle and process of thermoelectric conversion by thermocapacitive cycle and will guide the rational development of capacitive heat-to-current converters.","PeriodicalId":21,"journal":{"name":"ACS Nano","volume":"94 1","pages":""},"PeriodicalIF":17.1,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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