Interface-engineered Z-scheme of BiVO4/g-C3N4 photoanode for boosted photoelectrochemical water splitting and organic contaminant elimination under solar light

Although n-type bismuth vanadate (BiVO₄) is regarded as an attractive solar-light-active photoanode, its short carrier-diffusion length, sluggish oxidation kinetics, low electronic conductivity, and high recombination rate are the major intrinsic shortcomings that limit its practical application. To this end, the rational design of a solar-light-active, metal-free BiVO₄-based Z-scheme heterojunction photoanode is of great significance for achieving effective charge-separation features and maximum light utilization as well as boosting redox activity for efficient environmental treatment and photoelectrochemical water splitting. Herein, we propose a facile approach for the decoration of metal-free graphitic carbon nitride (g-C₃N₄) nanosheets on BiVO₄ to form a Z-scheme BiVO₄/g-C₃N₄ photoanode with boosted photoelectrochemical (PEC) water splitting and rapid photoelectrocatalytic degradation of methyl orange (MO) dye under simulated solar light. The successful preparation of the Z-scheme BiVO₄/g-C₃N₄ photoanode was confirmed by comprehensive structural, morphological, and optical analyses. Compared with the moderate photocurrent density of bare BiVO₄ (0.39 mA cm^-2), the Z-scheme BiVO₄/g-C₃N₄ photoanode yields a notable photocurrent density of 1.14 mA cm^-2 at 1.23 V vs. RHE (≈3-fold higher) with the promising long-term stability of 5 h without any significant photo-corrosion. Moreover, the PEC dye-degradation studies revealed that the Z-scheme BiVO₄/g-C₃N₄ photoanode successfully degraded MO (≈90%) in 75 min, signifying a 30% improvement over bare BiVO₄. This research paves the way for rational interface engineering of solar-light-active BiVO₄-based noble-metal-free Z-schemes for eco-friendly PEC water splitting and water remediation.

Effect of exposed facets of bismuth vanadate, controlled by ethanolamine, on oxidative coupling of primary amines

This work firstly demonstrates the ethanolamine (ETA)-assisted hydrothermal synthesis of BiVO₄, with different ratios of exposed {110}/{010} planes and relates this to performance in photocatalytic oxidative coupling of benzylamine under visible light. {110}-dominant BiVO₄ exhibits outstanding photocatalytic activity at room temperature owing to synergistic effects of largely exposed {110}-oxidative facet along with excellent charge generation and migration abilities, as evidenced by X-ray diffraction patterns, electrochemical impedance spectra, and photocurrent responses. The catalyst can successfully transform benzylamine derivatives to corresponding imines with selectivities of >85%, indicating a wide scope of amine substrates that can be used with the developed catalyst. Based on radical scavenging, spin-trapping EPR, and Mott-Schottky results, a plausible oxidative coupling mechanism via a O₂^--assisted route and band energy diagram of the catalyst are proposed. This work highlights the influence of ETA in controlling resultant exposed crystal facets of the final BiVO₄, which is the main factor governing oxidative amine coupling activity. Importantly, the tunability of exposed {110}/{010} facet of BiVO₄ controlled by ETA as well as a correlation between {110} facet and the coupling activity of benzylamine firstly disclosed in this work could be readily extended for designing functional catalysts with desired performances.

BiVO4 tubular structures: oxygen defect-rich and largely exposed reactive {010} facets synergistically boost photocatalytic water oxidation and the selective NN coupling reaction of 5-amino-1H-tetrazole

Oxygen defect-rich monoclinic BiVO₄ nanotubes with largely exposed active {010} facets were designed to exhibit impressive photocatalytic performance for both water oxidation and the selective NN coupling reaction of 5-amino-1H-tetrazole.

Preparation and photocatalytic activity characterization of activated carbon fiber-BiVO4 composites

Herein, we describe the hydrothermal immobilization of BiVO₄ on activated carbon fibers (ACFs) and characterize the obtained composite by several instrumental techniques, using Reactive Black KN-B (RB5) as a model pollutant for photocatalytic performance evaluation and establishing the experimental conditions yielding maximal photocatalytic activity. The photocatalytic degradation of RB5 is well fitted by a first-order kinetic model, and the good cycling stability and durability of BiVO₄@ACFs highlight the potential applicability of the proposed composite. The enhanced photocatalytic activity of BiVO₄@ACFs compared to those of BiVO₄ and ACFs individually was mechanistically rationalized, and the suggested mechanism was verified by ultraviolet-visible spectroscopy, attenuated total reflectance Fourier-transform infrared spectroscopy, and RB5 degradation experiments. Thus, this work contributes to the development of BiVO₄@ACF composites as effective photocatalysts for environmental remediation applications.

Herein, we describe the hydrothermal immobilization of BiVO₄ on activated carbon fibers, using Reactive Black KN-B photocatalytic performance evaluation and establishing the experimental conditions yielding maximalphotocatalytic activity.