Light-Driven Enhancement of Oxygen Evolution for Clean Energy Conversion: Co 3 O 4 -TiO 2 /CNTs P-N Heterojunction Catalysts Enabling Efficient Carrier Separation and Reduced Overpotential

In the renewable energy conversion system, water electrolysis technology is widely regarded as the core means to achieve clean hydrogen production. However, the anodic oxygen evolution reaction (OER) has become a key bottleneck limiting the overall water splitting efficiency due to its slow kinetic process and high overpotential. This study proposes a novel Co 3 O 4 -TiO 2 /CNTs p-n heterojunction catalyst, which was synthesized by hydrothermal method and significantly improved OER activity by combining heterojunction interface regulation and light field enhancement mechanism. Under illumination conditions, the catalyst achieved an overpotential of 390 mV at a current density of 10 mA cm −2 , which is superior to the performance of the dark state (410 mV) and single component Co 3 O 4 -TiO 2 catalysts. The material characterization results indicate that the p-n heterojunction structure effectively promotes the separation and migration of photogenerated carriers and enhances the visible light absorption capability. This work expands the design ideas of energy catalytic materials by constructing a collaborative electric light dual field regulation system, providing a new strategy for developing efficient and low-energy water splitting electrocatalysts, which is expected to play an important role in the future clean energy production and storage field.