Northwest Minzu University

The catalytic performance of tyrosinase (TYR) is highly sensitive to its microenvironment, which poses challenges for its application in immobilized systems. Here, we systematically investigated the effects of different liquid-phase environments (organic solvents and ions) on TYR activity using molecular dynamics (MD) simulations and experimental assays. The results showed that TYR maintained its overall structural integrity in all tested environments, whereas its catalytic activity varied considerably. Global structural parameters (RMSD, Rg, SASA) reflected solvent-induced conformational changes and showed correlations with activity variations. Further analysis of local dynamics via RMSF, secondary structure (DSSP), and the coordination geometry of the Cu^2 + -histidine catalytic center suggested that increased flexibility near the catalytic pocket might be associated with activity loss. Based on these findings, solvents that minimize local flexibility changes and avoid direct interaction with the catalytic center are considered preferable for preserving activity. Moreover, we propose a carrier design consisting of an Fe₃O₄ magnetic core coated with highly chlorinated polyvinyl chloride (CPVC), with Cu²⁺ incorporated during coating to potentially help maintain active-site integrity. This work provides preliminary insights into the relationship between microenvironment, structural dynamics, and enzyme activity, and offers guidance for solvent selection and the design of immobilized enzyme systems.

Despite its significant promise for photoelectrochemical (PEC) water splitting, the practical efficiency of bismuth vanadate (BiVO₄) is severely constrained by rapid bulk charge recombination and sluggish surface water oxidation kinetics. Coupling a hole transport layer (HTL) with an oxygen evolution cocatalyst (OEC) constitutes a highly effective strategy to circumvent these limitations. Herein, we report a rationally designed photoanode architecture comprising Mo-doped BiVO₄, an FeOOH HTL, and a novel urea-bridged perylene diimide polymer coordinated with Co and Fe ions (PDICF) as the OEC (denoted as Mo:BiVO₄/FeOOH/PDICF). Crucially, the interfacial synergy among these integrated layers dramatically amplifies PEC performance. The abundant O and N atoms within the PDICF matrix coordinate with Fe sites in the underlying FeOOH, establishing high-speed charge-transfer channels for efficient hole extraction. Within the PDICF framework, Co centers act as primary active sites, synergistically modulated by adjacent Fe ions. Density functional theory (DFT) simulations elucidate that strong FeCo orbital coupling facilitates rapid electron transfer and stabilizes the valence states of the active centers, thereby significantly lowering the activation energy barrier for the oxygen evolution reaction (OER). Consequently, the optimized photoanode achieves an exceptional photocurrent density of 5.6 mA cm^-2 at 1.23 V versus the reversible hydrogen electrode (RHE). Furthermore, the uniform PDICF coating effectively mitigates photocorrosion, sustaining a robust current density of 5.28 mA cm^-2 with outstanding long-term durability. This study provides profound insights into synergistic interface and catalyst engineering, offering a robust paradigm for the design of highly efficient and stable PEC systems.