Electronic engineering of transition metal Zn-doped InGaN nanorods arrays for photoelectrochemical water splitting.

The fast charge carrier recombination and slow oxidation kinetics of ternary semiconductor InGaN as promising photocatalyst impede the PEC performance. Herein, we fabricate transition metal zinc (Zn) doped InGaN nanorods arrays by radio-frequency plasma-assisted molecular beam epitaxy. The doping obviously reduces indium atoms composition, the aggregation of In–In and induces the deep energy level. This greatly decreases the defects and improves the valence band potential of InGaN nanorods, which is beneficial for the rapid carrier separation efficiency with the decreased photogenerated carrier recombination rate and improved water oxidation kinetics. Significantly, Zn doped InGaN nanorods photoanode shows three times higher photocurrent density of 1.65 mA/cm2 at 1.23 V versus reversible hydrogen electrode (RHE) compared to undoped InGaN nanorods (0.58 mA/cm2). More importantly, after loading Au nanoparticles, the maximum applied bias photo-to-current efficiency of Zn-doped nanorods photoanode reaches 1.33%, which is superior to the recent results of reported Zn doped based photoanodes. This efficient doping strategy not only bridges the gaps of heteroatom doped InGaN nanorods based photoelectrodes, but also provides deep insights into controlling the electronic structure, and crystallinity of photoelectrodes for enhanced solar converting efficiency. Image 1 • Highly efficient Zn-doped InGaN NRs photoanodes are prepared. • Photogenerated carrier recombination is suppressed for Zn-doped InGaN NRs. • Zn doping contributes to the positive shift of valence band. • High photovoltage for Zn-doped InGaN NRs is achieved. [ABSTRACT FROM AUTHOR]