A multi-functional photocatalyst, that can combine the catalytic functions of water oxidation and proton reduction together with light harvesting capacity, is highly desired for low cost, high efficiency, and highly stable solar fuel production. Monolayer WSe₂, with a direct energy gap of ~ 1.65 eV is a nearly ideal light absorber to convert sunlight to hydrogen fuels through solar water splitting. To date, however, the controlled synthesis of monolayer WSe₂ on a wafer scale and the realization of overall water splitting on WSe₂ have remained elusive. Here, we report the van de Waals epitaxy of crystalline monolayer WSe₂ on large area amorphous SiO_x substrates. We have demonstrated, for the first time, the multi-functionality of monolayer WSe₂ in solar water splitting, including extraordinary capacities for efficient light harvesting, water oxidation, and proton reduction. The absorbed photon conversion efficiency exceeds 12% for a single monolayer WSe₂. This work provides a viable strategy for wafer-scale synthesis of multi-functional photocatalysts for the development of efficient, low cost, and scalable solar fuel devices and systems.

对于低成本，高效率和高度稳定的太阳能燃料生产，迫切需要一种能够将水氧化和质子还原的催化功能与光收集能力相结合的多功能光催化剂。具有约1.65 eV的直接能隙的单层WSe ₂是近乎理想的光吸收剂，可通过分解太阳能将阳光转化为氢燃料。迄今为止，然而，单层的控制合成WSE ₂上的晶片规模和整体水分解的上WSE实现₂仍然难以实现。在这里，我们报告了大面积非晶SiO _x上晶体单层WSe _2的范德华外延基材。我们首次展示了单层WSe ₂在太阳能水分解中的多功能性，包括高效采光，水氧化和质子还原的非凡能力。对于单个单层WSe ₂，吸收的光子转换效率超过12％。这项工作为多功能光催化剂的晶圆规模合成提供了可行的策略，以开发高效，低成本和可扩展的太阳能设备和系统。