Spatiotemporal Coupling Dual-photocatalytic Integration in Atomic- hybridized Co0.5Fe0.5In2S4 Nanoflowers for High Efficiency Nitrogen Reduction

Abstract The photocatalytic reduction of N2 to NH3 under mild conditions using low-cost solar is an attractive alternative to replace the energy-intensive Haber-Bosch process, but which is typically hampered by poor binding of N2 to catalysts and high activation energy of intermediates. In particular time window, catalyst hydrogenation directly induced by photocatalytic water splitting can provide an alternation pathway to overcome limitations in conventional N2 reduction reaction (NRR). Herein, we propose a spatiotemporal coupling strategy in Co0.5Fe0.5In2S4 ultrathin nanoflowers to integrate hydrogen evolution reaction (HER) and NRR together, in which the photo-excited carrier life time is intentionally extended to match six-electron NRR process; meanwhile hydrogen evolution rate is limited to generate a transient hydrogenation on catalytic surface for accelerating N2 adsorption and activation. This spatiotemporal coupling design can easily drive N2 to *N2H2 and far away from conventional stagewise activation of N≡N triplet bonds. As a result, the photocatalytic performance of N2 reduction is about 85.8 μmol g-1 h-1 without sacrificial agent. Our findings provide a new paradigm for integrating dual photocatalytic reduction, bringing a transient hydrogenation and free nitrogen directly to reactants without requiring N2 molecular adsorption to the catalyst.