Nanotip-Engineered TiO₂ Photoanodes Enable Efficient Hydroxyl Radical Synthesis via Selective Water Oxidation

Hydroxyl radicals (·OH) are pivotal for green synthesis, anticancer therapy, and environmental remediation, yet controllable synthesis remains challenging. Photoelectrochemical single-electron water oxidation (1e^- WOR) provides a sustainable route for on-demand ·OH generation but is hindered by competing 4e^- oxidation pathways and sluggish interfacial mass transport. Here, we overcome these limitations through a nanotip engineering strategy that integrates synergistic microfield regulation and interface optimization. Using TiO₂ nanocones, we demonstrate nanotip-generated localized positive-charge-enhanced electric fields and reagent/temperature gradients. This configuration enhances OH^- adsorption, elevates the *OH → *O energy barrier, and boosts mass transport, collectively promoting ·OH generation. Furthermore, inherent aerophobicity enables rapid O₂ bubble detachment, suppressing detrimental *OH-O₂ hydrogen bonding (thermodynamically favoring the 1e^- pathway) while dynamically renewing active sites (kinetically reducing steric hindrance). These synergistic effects yield a record ·OH synthesis rate (∼92.2 μM/min) and near-complete pollutant degradation (>6.7-fold enhancement over previous reports). Our work establishes rational design principles for high-efficiency ·OH-driven photoelectrodes.