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

本项目旨在开发二维过渡金属二硫族化合物（TMDCs）的合成新路线，用于太阳能驱动的水分解。正如我们在研究计划中指出的，在HER过程中，抑制单层TMDCs发展的主要关键问题有三个：1)单层TMDCs的低产量生产；2) TMDCs的惰性基面；3)制备1T金属相TMDCs的条件苛刻。在过去的一年里，我们实现了大规模的单层MoS2和WS2纳米片的合成，包括相变。在这一年里，我们主要研究了惰性基面改性和TMDCs的尺寸效应。通过基面上的缺陷位控制和元素置换，使MoS2的惰性基面重新活化，大大拓宽了其可用性。通过对煅烧温度的控制，合成了具有不同催化氢活性的结晶依赖性单层二硫化钼。通过结晶度控制和基面上钴取代相结合，优化了催化氢活性，在420 nm可见光照射下实现了高达80.2%的量子效率。此外，通过尺寸控制，我们成功地在TiO2上合成了仅为~2 nm的超小无定形MoSx纳米点。由于尖锐的边缘效应，超小的非晶MoSx纳米点具有大量的HER活性位点，从而显著增强了催化析氢的活性。

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.