Highly Efficient InGaN Nanorods Photoelectrode by Constructing Z-scheme Charge Transfer System for Unbiased Water Splitting.

Unbiased photoelectrochemical water splitting for the promising InGaN nanorods photoelectrode is highly desirable, but it is practically hindered by the serious recombination of charge carrier in bulk and surface of InGaN nanorods. Herein, an unbiased Z-scheme InGaN nanorods/Cu O nanoparticles heterostructured system with boosted interfacial charge transfer is constructed for the first time. The introduced Cu O nanoparticles pose double-sided effect on photoelectrochemical (PEC) performance of InGaN nanorods, which enables a robust hybrid structure and induces weakened light absorption capability simultaneously. As a result, the optimized InGaN/Cu O-1.5C photoelectrode with the uniform morphology exhibits an enhanced photocurrent density of ≈170 µA cm at 0 V versus Pt, with 8.5-fold enhancement compared with pure InGaN nanorods. Comprehensive investigations into experimental results and theoretical calculations reveal that the electrons accumulation and holes depletion of Cu O facilitate to form a typical Z-scheme band alignment, thus providing a large photovoltage to drive unbiased water splitting and enhancing the stability of Cu O. This work provides a novel and facile strategy to achieve InGaN nanorods and other catalyst-based PEC water splitting without external bias, and to relieve the bottlenecks of charge transfer dynamics at the electrode bulk and electrode/electrolyte interface by constructing Z-scheme heterostructure.