Enhancing Photoelectrochemical Oxygen Demand Detection by Superhydrophobic and Surface‐Passivated Cocatalyst Engineering

Photoelectrochemical oxygen demand (PeCOD) technology has attracted significant attention in water quality monitoring due to its advantages of rapid analysis and avoidance of highly toxic reagents. However, the increasing diversity of water pollutants (including biomass derivatives, petroleum byproducts, and plastics byproducts) poses a new challenge to the broad-spectrum detection capability of photoanodes. Herein, calcination transformed the BiVO₄ photoanode modified with polytrithiophene (pTTh) and NiOOH cocatalysts, yielding a superhydrophobic BiVO₄ photoanode with amorphous nickel oxide (NiO_x) and sulfur-incorporated carbon cocatalysts (NiO_x/SC). The NiO_x/SC/BiVO₄ photoanode not only has higher photovoltage through surface defect passivation, but also enhances the selectivity for organic oxidation reactions by suppressing competitive water splitting. The NiO_x/SC/BiVO₄ photoanode shows excellent detection performance in biomass, petroleum byproducts and plastic byproducts represented by glucose, glycerol, and ethylene glycol, with a linear detection range of 192-19200 ppm (R² = 0.9953) and a detection limit of 1 mm (S/N = 14). The synergistic effect of the surface defect passivation and the hydrophobic modification provides an efficient and stable solution for broad-spectrum pollutant detection. This study not only provides material design strategies for the practical application of the PeCOD detection sensor, but also establishes a novel approach for rapid monitoring of complex aqueous systems.