In situ X-ray absorption spectroscopy to study redox dynamics in Ni and Cu co-catalysts on porous TiO2 photocatalyst films during H2 evolution

• Photocatalytic H 2 evolution activity trend follows the order NiCu > Ni > Cu – TiO 2 • In situ X-ray Absorption Spectroscopy tracks Ni and Cu oxidation state during photocatalysis • Spectroscopic results analyzed in relation to H 2 transients under UV light off/on/off cycles • Cu serves as an efficient electron sink for hydrogen evolution • Ni acts as a dynamic hole buffer through reversible oxidation