Temperature-modulated cocatalyst anchoring influences reaction-specific photocatalytic performance

Cocatalyst deposition on semiconductor surfaces is traditionally interpreted through photochemical frameworks where illumination dictates charge-carrier localization. Temperature, conversely, is typically relegated to a passive kinetic role, assumed only to accelerate diffusion and stochastic nucleation. Here, we provide evidence for a previously underappreciated contribution to this process: in the absence of light, deposition temperature appears to bias the interfacial electronic environments on graphitic carbon nitride (g-C₃N₄) that are available for cocatalyst anchoring. Across a narrow temperature window of 5-25 °C, we reveal a non-monotonic Pt-loading profile, motivating an examination of distinct anchoring environments beyond a simple picture of thermally accelerated deposition. Spectroscopic analysis, including time-resolved photoluminescence and nitrogen-specific chemical signatures, together with theoretical calculations supports temperature-dependent differences in local coordination and nitrogen-site preference. We propose that illumination and temperature operate hierarchically: light influences the domains accessible for photodeposition, while temperature further biases the local environments in which cocatalysts anchor. This dual-parameter framework connects anchoring-site differentiation with reaction-specific requirements. Specifically, we observe a reversal in relative activity ranking between ethylene glycol and triethanolamine sacrificial pathways across thermally conditioned catalysts, consistent with differences in the matching between interfacial electronic environments and pathway-specific charge-transfer demands. When this investigation was extended to Au/g-C₃N₄ and Pt/TiO₂, both systems also displayed temperature-dependent but material-specific responses. Our results identify temperature-sensitive metal-support interactions as a basis for understanding cocatalyst anchoring and provide a framework for investigating how environmental conditions influence interfacial site preference.