Branched Nanowire Heterostructures for Efficient and Durable Solar-Driven Hydrogen Production

Branched nanowire (NW) heterostructures have recently been attracted considerable attention for solar water splitting and clean hydrogen production due to their unique properties such as nanoscale integration of different functional materials, greatly enhanced junction and surface area, enhanced gas evolution efficiency, broadband light absorption, etc. Moreover, branched NWs can be fabricated using facile and scalable fabrication methods such as hydrothermal or solvothermal growth methods. In this presentation, we show branched NWs of different compositions for core (or trunk) and branch NWs which were fabricated with facile and low-cost synthesis methods using cheap, non-toxic, and earth abundant materials including Si, CuO, Cu₂O, ZnO, TiO₂, and Fe₂O₃. The branched NW structures and the heterostructures’ interfaces are investigated in detail using different characterization techniques such as SEM/HRSEM, TEM/HRTEM, STEM/HRSETM, etc. The photoelectrochemical (PEC) performances including photocurrent turn-on potential, photocurrent, solar conversion efficiency, and incident photon-to-current efficiency (IPCE) are studied systematically and optimized, based on different core and branch NW dimensions, for each specific branched NW heterostructure to provide efficient water splitting in a neutral medium. The electrode stability of different branched NWs is also investigated and long-term stability of over one day or several hours using a thin passivation layer or robust branched NWs are presented. The achieved results pave the way for accomplishing spontaneous overall solar water splitting for clean, efficient, cost-effective and durable solar hydrogen generation at large scales.