Highly efficient hydrogen production via photothermal-catalytic methanol steam reforming over high-entropy metal oxides.

Methanol steam reforming holds great promise for on-demand hydrogen production under mild conditions. However, the development of catalysts with high activity, effective CO suppression, and efficient solar energy utilization remains a formidable challenge. Here, we present a high-entropy oxide catalyst, CuCeZrLaCrOx, featuring a dominant La2Ce2O7 pyrochlore phase, which enables efficient hydrogen production via a synergistic photothermal mechanism under full-spectrum light irradiation. Mechanistic studies reveal that methanol steam reforming on this catalyst mainly proceeds via the formate pathway. Light irradiation plays a crucial role by modulating defect-associated electronic states, reducing the apparent activation energy, and facilitating interfacial redox processes that accelerate H2 generation. The CuCeZrLaCrOx-450 catalyst demonstrates high performance, achieving a H2 production rate of 579.8 mmol g-1 h-1 at ∼12 suns, with CO selectivity below 0.5%. Outdoor experiments under natural sunlight further confirm its robustness, with H2 production rates reaching up to 400 mmol h-1, maintaining over 99% selectivity for H2, and keeping CO and CH4 selectivities below 1%. This work demonstrates the potential of high-entropy oxides as tunable, self-regulating photothermal catalysts and offers new mechanistic insights for the design of solar-driven hydrogen generation systems.