Superhydrophobic Photochromic TiO2/Bi2WO6 Materials Promote Photocatalytic CO2 Reduction under Visible Light Irradiation

Photocatalytic CO₂ reduction to renewable fuels presents a promising strategy to mitigate greenhouse effects, yet challenges persist in achieving high efficiency due to CO₂'s thermodynamic stability and competitive H₂O adsorption. Herein, we develop a superhydrophobic photochromic TiO₂/Bi₂Wo₆ (TBW-2O) nanocomposite that synergistically enhances visible-light-driven CO₂ reduction. Dynamic charge management via reversible W⁶⁺↔W⁵⁺ transitions not only suppresses charge recombination but also facilitates electron transfer for CO₂ activation, as evidenced by in situ XPS and EPR. The superhydrophobic surface designed with sodium oleate (water contact angle >150°) selectively enriches CO₂ at the active sites compared to H₂O (ΔG_CO2 = -2.88 eV vs ΔG_H2O = -1.17 eV). Dual heterojunction effects (Type II + Z-scheme) between TiO₂ and Bi₂WO₆ optimize light absorption and redox potentials. The optimized TBW-2O achieves exceptional CH₄ and CO production rates of 48.09 and 37.40 μmol·g^-1·h^-1, respectively, representing 19.7- and 6.6-fold enhancements over pure TiO₂. Notably, it attains an apparent quantum yield (AQY) of 0.35% (CH₄) and 0.32% (CO) at 350 nm without sacrificial agents or noble metals. Combined experimental and theoretical analyses reveal that the W⁶⁺/W⁵⁺ redox cycle and hydrophobic interface collaboratively promote COOH/CHO intermediate formation, steering the reaction pathway toward CH₄. This work provides a design blueprint for multifunctional photocatalysts integrating photochromism and surface wettability control.