Ru-TiO2/Ti2C for photocatalytic in-situ atmospheric-pressure hydrogen storage: insights into H* transport and bonding behaviors

Photocatalytic water splitting is a promising approach for sustainable green hydrogen production, but its practical deployment is severely hindered by two critical limitations: mandatory H 2 /O 2 separation and the requirement for high-pressure hydrogen storage facilities. To address this long-standing bottleneck, a Ru-TiO 2 /Ti 2 C heterostructured photocatalyst is fabricated via a combined hydrothermal and ball-milling route. Operando spectroscopy and DFT calculations verify a cascade charge and hydrogen transfer pathway: photogenerated electrons migrate from TiO 2 to metallic Ru sites to drive water dissociation into surface H* intermediates, which then spillover onto the Ti 2 C substrate. Owing to the strong atomic hydrogen affinity of Ti 2 C, accumulated H* is immobilized in the Ti 2 C lattice via Ti-H covalent bonds, achieving in-situ atmospheric-pressure hydrogen storage. The optimized composite exhibits an in-situ hydrogen storage capacity of 2.1 wt% at ambient temperature and pressure, with a markedly reduced desorption temperature of 216°C and excellent cycling durability. This work establishes an integrated paradigm of photocatalytic water splitting and low-pressure hydrogen storage, offering a feasible strategy to resolve the inherent H 2 /O 2 separation dilemma and advance the practical application of solar-driven hydrogen production.