Unlocking Built‐In Polarization via Single‐Atom Nickel Engineering in Hexagonal Cavities for Efficient Photoreforming of Biomass

ABSTRACT Rapid bulk charge recombination in crystalline semiconductors remains a critical bottleneck hindering the scalability of photocatalytic hydrogen generation. Here, we report that precise anchoring of single‐atom nickel into the hexagonal cavities of crystalline Zn 3 In 4 S 9 activates a strong built‐in polarization electric field (PEF), which dramatically enhances charge separation. The optimized Ni 0.4 ‐Zn 3 In 4 S 9 shows hydrogen production and benzaldehyde (BAD) generation rates of 48.14 and 44.72 mmol g −1 h −1 , respectively, corresponding to 22.3‐ and 17.4‐fold enhancements over the Zn 3 In 4 S 9 . It also exhibits a 42.9% apparent quantum yield at 420 nm and exceptional stability, maintaining over 94.2% (H 2 ) and 89.2% (BAD) activity after 48 h with 6.28‐ and 14.4‐fold stability enhancement for hydrogen and BAD production, respectively. This work proposes an atomic‐level design strategy for activating PEF in Zn 3 In 4 S 9 hexagonal cavities, enabling highly efficient photoreforming of biomass derivatives.