Towards sustainable photoelectrodes for solar to hydrogen conversion through the combination of earth-abundant elements

Abstract

Abstract Hematite nanostructures are strong candidates for the development of sustainable water splitting technologies. However, major challenges exist on improving charge density and minimizing charge recombination rates for a competitive photoelectrochemical performance based on hematite without compromising sustainability aspects. Here we develop a synthetic strategy to leverage earth-abundant Al3+ and Zr4+ in a dual-chemical modification to synergistically minimize small polaron effects and interfacial charge recombination. The solution-based method simultaneously induces Al3+ to dope the hematite crystal lattice while Zr4+ forms interfacial excess, creating a single-phased homogenous nanostructured thin film. The engineered photoanode increased photocurrent from 0.7 mA cm− 2 for pristine hematite up to 4.5 mA cm− 2 at 1.23V and beyond 6.0 mA cm− 2 when applying an overpotential of 300mV under simulated sunlight illumination (100 mW cm− 2). The results demonstrate the potential of dual-modification design using solution-based processes to enable sustainable energy technologies.