Ni0-Ni2+ dual-active-center and p-n heterojunction in 3DOM NiOx-TiO2 composites enhancing photocatalytic hydrogen production

3DOM NT-AH was obtained via synergistic reduction integrates Ni0/Ni2+ dual active centers and a NiO/TiO2 p-n heterojunction, enhancing electron transfer and charge separation to achieve a 16-fold increase in H2 evolution over unreduced 3DOM NT. Nickel oxide (NiO), owing to its tunable valence states and non-noble-metal cocatalytic properties, has shown great potential in photocatalytic hydrogen evolution. However, challenges remain in achieving highly dispersed loading, precise valence regulation, and optimized interfacial structures. Herein, we establish the Ni 0 /Ni 2+ dual active centers and NiO/TiO 2 p-n heterojunction in three-dimensionally ordered macroporous NiO x -TiO 2 -AH (3DOM NT-AH) composite photocatalyst for photocatalytic hydrogen production. In this unique structure, Ni 2+ species are favorable for forming a tightly coupled interfacial p-n heterojunction with TiO 2 , thereby promoting interfacial charge separation and directional carrier migration, while metallic Ni 0 acts as an efficient electron sink and electron-transfer mediator, facilitating rapid electron extraction and transport. Meanwhile, the highly dispersed NiO x nanoparticles are intimately anchored on the 3DOM TiO 2 (3DOM T) framework forming p-n heterojunction, further enhancing interfacial electron transfer and suppressing the recombination of photogenerated electron-hole pairs. The synergistic effect of the Ni 0 /Ni 2+ dual active centers and the p-n heterojunction makes that the optimized 3DOM NT-AH sample exhibits excellent photocatalytic hydrogen evolution performance, achieving a hydrogen evolution rate of 3.60 mmol·g −1 ·h −1 , which is about 16 times that of the unreduced 3DOM NiO-TiO 2 (3DOM NT) sample. This work provides a promising strategy for the design of efficient non-noble-metal Ni-based photocatalysts. Download: Download high-res image (201KB) Download: Download full-size image