Reconfiguring Charge Spatial Distribution in One-Dimensional AuAg Alloy Nanoarrays

Plasmonic metal/semiconductor heterostructures have emerged as a promising strategy for enhancing solar-driven photocatalysis owing to the surface plasmon resonance (SPR) effect. However, the associated optical fields are typically confined near the metal/semiconductor interface, limiting the spatial separation of hot carriers and leading to inefficient charge utilization. Here, we address this challenge by exploiting one-dimensional surface lattice resonance (1D-SLR) in ordered AuAg nanoarrays on SrTiO₃ substrates based on finite element method (FEM) simulations. Single-particle surface photovoltage (SPV) microscopy shows that, unlike conventional SPR, 1D-SLRs not only enhance hot electron generation but also promote a spatially extended distribution of photogenerated holes across the nanoparticle surfaces. Coupling these arrays with a CoO_<i>x</i> cocatalyst yields a 23-fold increase in the incident photon-to-current efficiency (IPCE) for photoelectrochemical water oxidation. This work highlights the potential of SLR engineering to simultaneously optimize light harvesting and interfacial charge dynamics, offering a new paradigm for efficient solar energy conversion.