Hierarchical InN/PNM/IPQ photoanode with enhanced interfacial charge transfer for efficient PEC water oxidation

A hierarchical InN/Ni/InP photoanode is constructed. • Type-II heterojunction and metal contacts promote efficient charge separation. • The photoanode delivers high photocurrent and near-unity Faradaic efficiency. • Interfacial charge transfer is accelerated by synergistic junction engineering. Photoelectrochemical (PEC) water splitting is frequently hindered by inefficient charge separation and sluggish interfacial charge-transfer kinetics. Here we report a hierarchical InN/PNM/IPQ photoanode composed of vertically aligned indium nitride nanorods (InN NRs), petal-like nickel microspheres (P-Ni MSs), and indium phosphide quantum dots (InP QDs). In this architecture, the InP QDs establish a type-II InN/InP heterojunction that promotes spatial charge separation, whereas the P-Ni MSs provide efficient electrical contact and facilitate interfacial charge extraction. Consequently, the InN/PNM/IPQ photoanode delivers a photocurrent density of 6.89 mA cm −2 at 1.45 V RHE and an ABPE of 1.21% at 0.86 V RHE , surpassing those of the pristine InN and the corresponding binary photoelectrodes. Under AM 1.5G illumination, it also exhibits a hydrogen evolution rate of 289.8 μmol h −1 , a Faradaic efficiency of 97.6% and stable PEC output over 8500 s. Electrochemical impedance spectroscopy and transient photocurrent measurements reveal suppressed charge recombination and accelerated interfacial charge transfer, in agreement with the synergistic effects of type-II band alignment and metal–semiconductor junction engineering. This work demonstrates an effective hierarchical heterostructure design for enhancing the performance of InN-based photoelectrodes toward solar-driven PEC water splitting. A hierarchical photoanode composed of indium nitride nanorods, petal-like nickel microspheres, and indium phosphide quantum dots is constructed to enhance photoelectrochemical water splitting. The synergistic effects of a type-II heterojunction and optimized metal–semiconductor interfaces promote efficient charge separation and interfacial charge transfer, resulting in improved photocurrent density, stability, and Faradaic efficiency. Download: Download high-res image (182KB) Download: Download full-size image