In-situ H2/O2 separation in photocatalytic water splitting by hydrogen spillover-driven hydrogen storage on Ru/WO3-MWCNTs

Photocatalytic water splitting is hindered by flammable H 2 /O 2 cogeneration and energy-intensive post-separation. Herein, a Ru/WO 3 -MWCNTs ternary composite is designed to address these bottlenecks via a hydrogen spillover-based strategy: direct H* storage instead of gaseous H 2 generation to achieve H 2 /O 2 separation. Photogenerated H* from Ru active sites migrate through WO 3 , then is immobilized on MWCNTs as C H bonds for hydrogen storage, enabling exclusive O 2 release during photocatalysis. This composite exhibits an oxygen evolution rate (OER) of 645.28 μmol g −1  h −1 (outperforming binary counterparts) with no detectable gaseous H₂ during irradiation, alongside a stable H₂ storage capacity of 2.23 wt%. The stored hydrogen is thermally releasable, and the entire cycle of photocatalytic water splitting (hydrogen storage with O 2 evolution) and thermal H 2 release maintains excellent cyclic stability. This work establishes hydrogen storage-aided in-situ H 2 /O 2 separation as a universal strategy for addressing the core bottlenecks in photocatalytic water splitting.