Enhanced Photocatalytic CO2 Reduction Performance by External Electric Field‐Driven Charge Separation on Interdigitated Micro‐Spacing Structure

ABSTRACT Traditional photoelectrocatalysis (PEC) separates photogenerated charge carriers via an external bias. However, its complex configuration and high‐resistance liquid electrolytes restrict its application largely to liquid‐phase systems. Taking advantage of the remarkable enhancement of the electric field gradient enabled by the interdigitated electrodes (IDEs) with a spacing of 100 µm, an external electric field‐enhanced photocatalytic CO ₂ reduction system was developed. A relatively high electric field strength can be generated under the application of a small external voltage. Given that the electric field strength is inversely proportional to the electrode spacing, when a 1.0 V is applied to electrodes with a 100 µm spacing, the electric field strength can reach the order of 104 V m ⁻¹ . By directly applying a modest external voltage (0.5–1.5 V) to hydrogenated TiO ₂ photocatalysts, an externally induced electric field drives the directional migration of charge carriers, enhancing the separation and transport of photogenerated carriers. At 1.5 V applied voltage, the hydrogenated TK ₄₅₀ catalyst achieves CH ₄ and C ₂ H ₆ production rates of 31.1 and 4.9 µmolg ⁻¹ h ⁻¹ , represents a four‐fold enhancement compared to the pristine TiO ₂ baseline. Consequently, the application of this electric field‐enhanced photocatalytic system to gas‐phase reaction for addressing energy and environmental challenges.