Electrochemically controlled CdS@CdSe nanoparticles on ITO@TiO₂ dual core–shell nanowires for enhanced photoelectrochemical hydrogen production

Here, we report a novel dual heterostructured photoanode consisting of CdS@CdSe core–shell nanoparticles (NPs) and 1D-structure tin-doped indium oxide (ITO)@TiO₂ core–shell nanowires (ITO@TiO₂@CdS@CdSe) for highly efficient photoelectrochemical (PEC) hydrogen production. The finely controlled hierarchical core–shell CdS@CdSe sensitization from consecutive electrochemical deposition on the ITO@TiO₂ core–shell nanowire has synergistic effects of visible-light utilization and efficient charge transport on the PEC response. The rationally designed dual core–shell heterostructure leads to cascade charge migration throughout the aligned energy band edges with rapid charge extraction through the hierarchical heterostructure of ITO@TiO₂@CdS@CdSe, alleviating the crucial charge accumulation. As a result, the dual heterostructured photoanode exhibits a maximum photocurrent density of 20.11 mA/cm² at 1.23 V vs. the reversible hydrogen electrode (RHE) and a dramatic enhancement in the incident photon-to-current efficiency (IPCE) over the extended absorption spectrum. The time-resolved photoluminescence (TRPL) characterization indicates the realized multiple-band cascade charge migration throughout ITO@TiO₂@CdS@CdSe could promote an 8-fold increase in the charge separation efficiency. This rational design of dual-heterojunction-structured photoelectrodes via electrochemical deposition provides a demonstration of modifying conventional light-harvesting photoelectrodes with stagnate solar energy conversion and PEC hydrogen production.