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

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.