Producing clean hydrogen directly from sunlight and water has emerged as a promising path for achieving carbon neutrality and environmental sustainability. However, the inefficient utilization of photogenerated charge carriers in photocatalysts hinders the solar-to-hydrogen efficiency. Here we show the use of excitonic quantum superlattice structures, consisting of nanometre-scale gallium nitride and indium gallium nitride, to achieve effective charge steering for photocatalytic overall water splitting. With this structure, the lifetime of photogenerated indirect excitons, composed of electrons and holes via Coulomb interaction, can be substantially prolonged by exploiting the quantum-confined Stark effect. As a result, photogenerated carriers can be effectively utilized for surface reactions, achieving high external quantum efficiency extended to visible light and a solar-to-hydrogen efficiency of 3.16% under ambient conditions and concentrated sunlight. Furthermore, outdoor scale-up demonstration achieved an average solar-to-hydrogen efficiency of 1.64% under 204-fold sunlight intensity.
Pan et al. (Fri,) studied this question.