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

我们的项目旨在开发新的路线来合成二维过渡金属二硫属化合物（TMDC），以应用于太阳能驱动的水裂解。正如我们在研究计划中指出的，在HER过程中存在三个主要的关键问题抑制单层TMDCs的发展：1）单层TMDCs的低产量生产; 2）TMDCs的惰性基面; 3）制备1 T金属相TMDCs的苛刻条件。在过去的一年里，我们实现了单层二硫化钼和WS 2纳米片的大规模合成，包括相变。本年度主要研究惰性基面的改性和TMDC的尺寸效应，通过缺陷位控制和基面上的元素替代，重新激活了MoS 2的惰性基面，显著拓宽了其可用性。通过控制焙烧温度，我们合成了具有不同催化氢活性的叠层结构依赖的单层二硫化钼。通过结晶度控制和钴基取代相结合，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，我们成功地合成了超小的非晶MoSx纳米点，只有~2 nm的助催化剂在TiO 2。由于锐边效应，超小非晶MoSx纳米点具有许多HER活性位点，因此显著增强了催化析氢活性。

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.