Interfacing semiconducting Nanowires (NWs) with potent electrocatalysts composed of earth-abundant elements will significantly improve their performance as photoelectrodes in Z-scheme artificial photosynthesis devices. Hydrogen evolution reaction (HER) whereby protons and electrons are combined into molecular hydrogen, a clean and high density energy carrier, is catalyzed most effectively by the Pt group metals, which are both expensive and scarce, prompting widespread efforts to discover cost-effective and earth abundant materials for their replacement. Transition metal sulfur centers, which naturally exist as active sites for hydrogen evolving enzymes nitrogenase and hydrogenase, and their solid state analogues have sparked intense research interest due to their promising HER activity. Our recent result has shown that the incomplete cubane-like clusters [Mo3S4] is an efficient co-catalyst for the evolution of hydrogen when coupled to GaP NWs, with significant increase in H2 production rate compared to bare GaP NW. The structure of the molecular catalyst was not stable and went through structural change during the hydrogen evolution reaction into solid state amorphous nanoparticles without deteriorating the catalytic activity. Combined characterization with Surface Enhanced Raman Spectroscopy, Aberration Corrected High Resolution TEM and X-ray Adsorption Spectroscopy studies have been conducted to interrogate the change in local structure observed at the catalyst/semiconductor interface. Such measurements are crucial for identifying active catalytic species, understanding the reaction mechanism and developing more efficient and stable transition metal sulfide catalyst.

Semiconductor nanowire-molybdenum interface for hydrogen evolution

246th National Meeting (2013)

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