Assisting vacancy-controlled Zn-BiVO₄photoanodes with trithiocyanuric-Co based metal-organic framework (n-p type-II heterojunction) for improving photoelectrochemical activity

Sustainable photocatalytic materials are promising candidates for renewable energy conversion. In this study, we synthesized Zn-doped BiVO4 photoanodes integrated with a cobalt-trithiocyanuric acid metal-organic framework (MOF) to enhance their photoelectrochemical (PEC) performance in water splitting to produce hydrogen. The introduction of the Zn dopant into the BiVO4 photoanode is advantageous for charge transport and suppressed recombination, while the MOF establishes an n-p type II heterojunction, improving charge separation and energy band alignment. Structural and compositional analyses confirmed the successful synthesis of the heterostructure. Electrochemical measurements revealed that the Zn-doped BiVO4/MOF (ZBM) photoanode achieved a photocurrent density of 2.03 mA/cm2 at 1.23 VRHE, which is approximately 3.5 times higher than that of pristine BiVO4 (0.58 mA/cm2) and 1.82 times higher than Zn-doped BiVO4 without MOF (ZB, 1.11 mA/cm2). Optical characterizations revealed enhanced light absorption and reduced charge-carrier recombination. These results highlight the potential of Zn-doped BiVO4 incorporated with an MOF as an efficient material for solar-driven energy conversion.