Heterojunction photoanode of SnO₂ and Mo-doped BiVO₄ for boosting photoelectrochemical performance and tetracycline hydrochloride degradation

The photoelectrochemical (PEC) method has a potential to harvest solar energy for sustainable energy and degrade contaminants. Herein, we fabricated cauliflower-like SnO₂ and porous Mo-doped BiVO₄ (SnO₂/Mo:BiVO₄) photoelectrodes by a sol-gel spin-coating method for better PEC performance and higher degradability of tetracycline hydrochloride (TC-HCl). The SnO₂ layer plays a crucial role in attaining a smooth and uniform surface of the photoanodes for blocking holes to defect trap sites and preventing charge recombination with improved light utilization. Mo dopants serve as nuclei for the crystallization of BiVO₄ and for making charge-adjustable porous structures for PEC performance. Thus, the content-optimized SnO₂/Mo:BiVO₄ photoanode film presents the highest photocurrent density of 0.59 mA cm⁻² at 1.23 V_RHE of 82.1% TC-HCl decomposition efficiency within 120 min at a rate constant of 1.49 × 10⁻² min⁻¹, providing a promising method for green environmental applications.