Design and Synthesis of Noble-Metal-Alternative Photo-catalysts for Solar Hydrogen Production

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Our project aimed to develop new routes for synthesis of two-dimensional transition metal dichalcogenides (TMDCs) for the application of solar-driven water splitting. As we indicated in the research plan, there are three main critical issues inhibiting the development of monolayer TMDCs during HER: 1) the low-yield production for monolayer TMDCs; 2) the inert basal plane of TMDCs; 3) harsh condition of preparing 1T metallic phased TMDCs. During the last year, we realized the large-scale synthesis of monolayer MoS2 and WS2 nanosheets, including the phase transformation. In this year, we mainly focused on the modification of inert basal plane and the size effect of TMDCs.Through the defect sites control and elemental substitution on the basal plane, we reactivated the inert basal plane of MoS2 and significantly broadened its usability. By control of the calcination temperature, we synthesized the crystallinity-dependent monolayer MoS2 which showed the different catalytic hydrogen activity. By combination of crystallinity control and cobalt substitution on the basal plane, we optimized the catalytic hydrogen activity, and realized a quantum efficiency as high as 80.2% under visible light irradiation at 420 nm. In addition, through the size control, we successfully synthesized the ultrasmall amorphous MoSx nanodots with only ~2 nm as the co-catalyst over TiO2. Due to the sharp edge effect, the ultrasmall amorphous MoSx nanodots possess numerous active sites for HER, and therefore significantly enhanced the activity for catalytic hydrogen evolution.