Dual‐Photoresponsive Z‐Scheme Heterojunction Catalysts via Linkage Chemistry‐Mediated Interface Engineering for Multi‐Field Coupled Regenerative Solar Seawater Batteries

ABSTRACT Here, we propose a linkage chemistry‐mediated interface engineering strategy to develop a class of photothermal/photoelectric dual‐responsive Z‐scheme heterojunction photoelectrodes featuring sulfonyl‐linked polymer semiconductor (S‐C 4 N) passivated Fe 2 O 3 nanorod arrays (Fe 2 O 3 NR), capable of overcoming sluggish near‐neutral oxygen reaction kinetics and insufficient sunlight utilization limitations for high‐efficiency multi‐field (optical‐electrical‐thermal‐chemical) coupled regenerative solar seawater batteries (MFCR‐SSB). By establishing a tunable heterocycle polymer platform, we perform detailed comparative study to scrutinize how the linkage chemistry influences photoresponsiveness and catalytic performance. Theoretical investigation reveals that compared to common C–C linkage, the electron withdrawing sulfonyl‐linkage can regulate local electron density to optimize intermediate adsorption for improved intrinsic oxygen evolution reaction (OER) activity. Meanwhile, it tailors energy landscape to induce Z‐scheme charge transfer path at S‐C 4 N@Fe 2 O 3 NR interfaces with 1.4‐time intensified built‐in electric field and additional Fe–O electron bridges for superior charge separation/transfer while imparting improved photothermal effect for rapid mass transport. All these facilitate reaction thermodynamics and kinetics in neutral media under illumination. Experimentally, the newly‐produced S‐C 4 N@Fe 2 O 3 NR heterojunction delivers significantly improved current response without/with bias voltage compared to C–C linked C 4 N@Fe 2 O 3 NR. The acquired MFCR‐SSB yields ultralow charge/discharge voltage gap of 0.17 V—surpassing most previous seawater batteries—alongside solar‐to‐electrochemical energy storage efficiency of 1.68%.