Unlocking the potential of atomic Ni reactive sites through interlayer confinement towards solar-to-hydrogen conversion from water

The atomization of active sites on photocatalysts facilitates a pronounced interaction with reactants, yet achieving a precise manipulation of the coordination environment of reactive atomic center remains challenging. Herein, we innovatively adopted polydopamine framework as an interlayer to maximize the density of Ni atomic sites, forming a unique atomic arrangement of Ni−N4 motif over CdS that delivers a remarkable photocatalytic H2 evolution of 44.34 mmol/h/g. DFT calculations, corroborated by experimental analyses, suggest an electron-deficient nature of isolated Ni which can facilitate a facile adsorption and local polarization of H2O molecules. The distinctive polydopamine interlayer not only serves as a new charge transfer channel, but also optimize the interaction between Ni sites and critical intermediates, rendering a prompt recombinative desorption of *H. This study offers unique perspectives on the collaborative interaction between the interlayer and the atomic active site, emphasizing their exceptional synergy for application in effective and sustainable catalytic conversions.