RSC Advances
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2012
·Vol. 3
·期 2
·616-622
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IF 0
Hui Liu,Weiwei Hu,Feng Ye,Yulong Ding,Jun Yang
Understanding the growth process of nanomaterials enables the control of their sizes/morphologies to enhance their performance for a given application. Herein we report the investigation into the synthesis of Ag2S nanocrystals by reacting Ag+ ions and/or Ag nanoparticles with S powder in a nonpolar organic solvent. The results show that the growth of Ag2S nanocrystals follows a “coalescence–fracture–ripening” mechanism, which is different from the commonly accepted LaMer nucleation growth model. At the initial stage of the reaction, Ag2S nanoclusters are formed on the surface of massive S powders and then coalesce to form extensive network of nanowires, which later are hollowed and fragmented into quasi-spherical particles due to the inside-out diffusion of S in nanowires. The quasi-spherical particles finally grow into uniform Ag2S nanocrystals through a ripening process. It has been found that the Ag2S growth process can be greatly accelerated by increasing the temperature of the reaction system and the sizes/morphologies of the final Ag2S nanocrystals can be easily tuned by varying the molar ratio of the starting precursors.
研究领域:
材料科学
·
化学
✓ 已验证
DOI
Catalysts
·
2020
·Vol. 10
·期 9
·948
·
IF 3.52
Chen Zhao,Zhi Yu,Jun Xing,Yuting Zou,Huiwen Liu,Hao Zhang,Weili Yu,Hicham Idriss,Chunlei Guo
The development of efficient electrocatalyst to produce molecular hydrogen from water is receiving considerable attention, in an effort to decrease our reliance on fossil fuels. The prevention of the aggregation of active sites during material synthesis, in order to increase charge transport properties of electrocatalysts, is needed. We have designed, synthesized, and studied a Ag2S/reduced graphene oxide (rGO) electrochemical catalyst (for hydrogen evolution) from water. The Ag2S nanocrystals were synthesized by the solvothermal method in which the rGO was added. The addition of the rGO resulted in the formation of smaller Ag2S nanocrystals, which consequently increased the electrical conductivity of the composite catalyst. The composite catalyst showed a higher electrochemical catalytic activity than the one with an absence of rGO. At a current density of 10 mA/cm2, a low overpotential of 120 mV was obtained. A Tafel slope of 49.1 mV/dec suggests a Volmer–Herovsky mechanism for the composite catalyst. These results may provide a novel strategy for developing hydrogen evolution reaction (HER) electrocatalysts, via the combining of a nano-semiconductor catalyst with a 2D material.Keywords:HER;Ag2S nanocrystals;reduced graphene oxide (rGO);electrocatalyst;composites
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 53
·期 16
·11355-11366
·
IF 2.993
Tang Shilin,He Chuansheng,Li Dong,Cai Wenhao,Fan Louzhen,Li Yunchao
To obtain dual active near-infrared (NIR) nanomaterial with strong absorption and emission properties, we report herein a novel precursor reactivity differentiation strategy, i.e., utilizing 1-octadecene (ODE)–Se having the ability to react with Ag salts much stronger and faster than ODE–thiourea, for single-step preparation of Ag 2 Se@Ag 2 S nanocrystals (NCs). With this strategy, we were able to synthesize high-quality Ag 2 Se@Ag 2 S NCs with both excellent NIR absorption and emission properties. Particularly, these nanocrystals possess a rather strong and sharp excitonic absorption peak with a full width at half maximum less than 70 nm and a maximum fluorescence quantum yield as high as 24.3%. Their appealing optical properties and structural features were founded to be highly dependent on the Se to S precursor ratio in the reaction solutions, owing to such a ratio exerting a direct influence on the core sizes and shell thicknesses of the as-formed NCs. Taking advantage of their remarkable NIR absorption properties, self-powered photoelectrochemical-type photodetectors based on the as-prepared Ag 2 Se@Ag 2 S NCs were successfully fabricated, which demonstrate a much better response performance and photostability in comparison with those based on Ag 2 Se NCs.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
CHEMISTRY OF MATERIALS
·
2023
·
IF 8.6
Jieyu Zhang,Jingjing Min,Binghan Li,Wenxing Yang,Zaiping Zeng,Dianyi Liu,Botao Ji
Environmentally friendly Ag2S nanocrystals (NCs) show potential applications as light-absorbing semiconductors for thin-film photovoltaics or biological taggants. However, thiol ligands are generally involved during the synthesis of Ag2S NCs to maintain colloidal stability, hindering postexchange of these crystal-bound thiolate ligands. Here, using common non-thiol ligands (oleic acid and oleylamine), we develop a general strategy of surface heterovalent-metal (Bi3+, Ga3+, In3+, Sb3+, and Zn2+) decoration to synthesize colloidal cation-rich Ag2S NCs achieving a high photoluminescence quantum yield up to 22% at ∼1230 nm. Density functional theory calculations reveal the heterovalent-metal cations exhibit stronger orbital coupling to the ligands than Ag atoms, and thus stronger binding affinity, resulting in reduced dynamic surface ligands to produce compact cation-rich Ag2S NCs with high solubility in nonpolar solvents. We further show that surface-decorated Bi atoms can accumulate the electron charge density, leading to surface-related band-edge emissions with increased electron–hole separation and prolonged exciton lifetimes of the Bi-decorated Ag2S NCs, which are desirable for many optoelectronic conversion applications. Using a 40 nm-thick light-absorbing layer of Bi-decorated Ag2S NCs, the optimized solar cells show a short-circuit current density of 18.6 mA cm–2 and a power conversion efficiency of over 4%.
研究领域:
材料科学
·
纳米技术
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光伏技术
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光电技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）