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Electron Inversion and Tunneling at Silicon Thermal Oxide Interfaces for Solar-Driven Molecular Catalysis to Syngas
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2025-03-18 , DOI: 10.1021/jacs.4c17251
Shi He 1 , Samuel R Bottum 1 , John C Dickenson 1 , Hannah R M Margavio 2 , Niklas D Keller 1 , Oluwaseun A Oyetade 1 , Ryan J Gentile 1 , Taylor S Teitsworth 1 , Samuel J Shin 1 , Jillian L Dempsey 1 , Alexander J M Miller 1 , Renato N Sampaio 1 , Stephen J Tereniak 1 , Carrie L Donley 1 , Matthew R Lockett 1 , Gregory N Parsons 2 , Gerald J Meyer 1 , James F Cahoon 1
Affiliation  

Semiconductor photoelectrodes are regularly coupled to solid-state heterogeneous catalysts to perform solar-driven reduction of CO2. Less frequently, molecular catalysts are employed to better control the reactivity toward desired products, yet the development of robust semiconductor/molecule interfaces has proven challenging. Here, we demonstrate that a 2–3 nm thermal oxide layer on Si exhibits stability in aqueous solution, high photovoltage, and a photocurrent density of ∼10 mA/cm2 for the solar-driven photoelectrochemical reduction of a homogeneous molecular catalyst, producing syngas with an ∼2:1 H2 to CO ratio. Because of a low defect density, the oxide interface forms an electron inversion layer with metal-like electron density at cathodic potentials. This inversion layer facilitates electron transfer to redox-active molecules via tunneling even if the molecule’s reduction potential is beyond the semiconductor’s conduction band edge. Using an electrolyte solution composed of a homogeneous cobalt bis(terpyridine) catalyst in a water/organic solvent mixture, stable photoelectrochemistry was observed under 1-sun illumination, exhibiting an ∼30% Faradaic efficiency for CO that was similar to a glassy carbon electrode under comparable conditions. The results demonstrate that an ultrathin thermal oxide interface is a robust platform for development of aqueous-stable, molecule-driven photoelectrocatalysis.

中文翻译:


硅热氧化物界面处的电子反转和隧穿,用于太阳能驱动分子催化合成气



半导体光电极定期与固态非均相催化剂偶联,以执行太阳能驱动的 CO2 还原。不太常见的是,分子催化剂用于更好地控制对所需产物的反应性,但事实证明,开发稳健的半导体/分子界面具有挑战性。在这里,我们证明 Si 上的 2-3 nm 热氧化层在水溶液中表现出稳定性、高光电压和 ∼10 mA/cm2 的光电流密度,用于太阳能驱动的光电化学还原均相分子催化剂,产生具有 ∼2:1 H2 与 CO 比的合成气。由于缺陷密度低,氧化物界面在阴极电位处形成具有类似金属电子密度的电子反转层。该反转层有助于通过隧穿将电子转移到氧化还原活性分子,即使分子的还原电位超出半导体的导带边缘。使用由水/有机溶剂混合物中的均相钴双(三吡啶)催化剂组成的电解质溶液,在 1 个太阳照射下观察到稳定的光电化学,对 CO 表现出 ∼30% 的法拉第效率,与同等条件下的玻璃碳电极相似。结果表明,超薄热氧化物界面是开发水稳定、分子驱动的光电催化的可靠平台。
更新日期:2025-03-19
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