BiOI/Bi2O2[BO2(OH)] heterojunction with boosted photocatalytic degradation performance for diverse pollutants under visible light irradiation

B and N Codoped Cellulose-Supported Ag-/Bi-Doped Mo(S,O)3 Trimetallic Sulfo-Oxide Catalyst for Photocatalytic H2 Evolution Reaction and 4-Nitrophenol Reduction

Cellulose plays a significant role in designing efficient and stable cellulose-based metallic catalysts, owing to its surface functionalities. Its hydroxyl groups are used as anchor sites for the nucleation and growth of metallic nanoparticles and, as a result, improve the stability and catalytic activity. Meanwhile, cellulose is also amenable to surface modifications to be more suitable for incorporating and stabilizing metallic nanoparticles. Herein, the Ag-/Bi-doped Mo(S,O)3 trimetallic sulfo-oxide anchored on B and N codoped cellulose (B-N-C) synthesized by a facile approach showed excellent stability and catalytic activity for PHER at 573.28 μmol/h H2 with 25 mg of catalyst under visible light, and 92.3% of the 4-nitrophenol (4-NP) reduction was achieved within 135 min by in situ-generated protons. In addition to B and N codoping, our use of the calcination method for B-N-C preparation further increases the structural disorders and defects, which act as anchoring sites for Ag-/Bi-doped Mo(S,O)3 nanoparticles. The Ag-/Bi-doped Mo(S,O)3@B-N-C surface active site also stimulates H2O molecule adsorption and activation kinetics and reduces the photogenerated charge carrier's recombination rate. The Mo4+ → Mo6+ electron hopping transport and the O 2p and Bi 6s orbital overlap facilitate the fast electron transfer by enhancing the electron's lifetime and photoinduced charge carrier mobility, respectively. In addition to acting as a support, B-N-C provides a highly conductive network that enhances charge transport, and the relocated electron in B-N-C activates the H2O molecule, which enables Ag-/Bi-doped Mo(S,O)3@B-N-C to have appreciable PHER performance.

Enhancing the Conductivity and Dielectric Characteristics of Bismuth Oxyiodide via Activated Carbon Doping

Activated carbon/BiOI nanocomposites were successfully synthesized through a simplistic method. The produced composites were then characterized using XRD, TEM, SEM-EDX, and XPS. The results showed that BiOI with a tetragonal crystal structure had been formed. The interaction between activated carbon and BiOI was confirmed via all the mentioned tools. The obtained nanocomposites' electrical conductivity, dielectric properties, and Ac impedance were studied at 59 KHz-1.29 MHz. AC and dc conductivities were studied at temperatures between 303 and 573 K within the frequency range of 59 KHz-1.29 MHz. The 10% activated carbon/BiOI nanocomposite possessed dc and AC conductivity values of 5.56 × 10-4 and 2.86 × 10-4 Ω-1.cm-1, respectively, which were higher than BiOI and the other nanocomposites. Every sample exhibited increased electrical conductivity values as the temperature and frequency rose, suggesting that all samples had semiconducting behavior. The loss and dielectric constants (ε' and ε″) also dropped as the frequency increased, leading to higher dielectric loss. The Nyquist plot unraveled single semicircle arcs and a decreased bulk resistance, indicating decreased grain boundary resistance. Consequently, the electrical characteristics of BiOI, 1C/BiOI, 5C/BiOI, and 10C/BiOI implied their applicability as dielectric absorbers, charge-stored capacitors, and high-frequency microwave devices.

Visible-light-driven AgI/Bi4O5I2 S-scheme heterojunction for efficient tetracycline hydrochloride removal: Mechanism and degradation pathway

The existence of excessive tetracycline hydrochloride (TCH) in the ecological environment has seriously threatened human health, so there is an urgent need to develop a high-performance photocatalyst that can efficiently and greenly remove TCH. Currently, most photocatalysts have the problems of fast recombination of photogenerated charge carriers and low degradation efficiency. Herein, S-scheme AgI/Bi₄O₅I₂ (AB) heterojunctions was constructed for TCH removal. Compared with the single component, the apparent kinetic constant of the 0.7AB is 5.6 and 10.2 time as high as the AgI and Bi₄O₅I₂, and the photocatalytic activity only decreases by 3.0% after four recycle runs. In addition, to verify the potential practical application of the fabricated AgI/Bi₄O₅I₂ nanocomposite, the photocatalytic degradation of TCH was performed under different conditions by regulating the dosage of photocatalyst, the TCH concentration, pH, and the existence of various anions. Systematical characterizations are conducted to investigate the intrinsic physical and chemical properties of the constructed AgI/Bi₄O₅I₂ composites. Based on the synergetic characterizations by in situ X-ray photoelectron spectroscopy, band edge measurements, as well as reactive oxygen species (ROS) detections, the S-scheme photocatalytic mechanism is proved. This work provides a valuable reference for developing efficient and stable S-scheme AgI/Bi₄O₅I₂ photocatalyst for TCH removal.

Efficient NO removal and photocatalysis mechanism over Bi-metal@Bi2O2[BO2(OH)] with oxygen vacancies

Photocatalysis technology prevails as a feasible option for air pollution control, in which high-efficiency charge separation and effective pollutant activation are the crucial issues. Here, this work designed Bi-metal@ Bi₂O₂[BO₂(OH)] with oxygen vacancies (OVs) catalyst for photocatalytic oxidation of NO under visible light, to shed light on the above two processes. Experimental characterizations and density functional theory (DFT) calculations reveal that a unique electron transfer covalent loop（[Bi₂O₂]²⁺ → Bi-metal → O^2-）can be formed during the reaction to guide the directional transfer of carriers, significantly improving the charge separation efficiency and the yield of active oxygen species. Simultaneously, the defect levels served by OVs also play a part. During the NO purification process, in-situ DRIFTS assisted with DFT calculations reveal that Bi metals could be functioned as electron donors to activate NO molecules and form NO^-, a key intermediate. This induces a new reaction path of NO → NO^- → NO₃^- to achieve the harmless conversion of NO, effectively restraining the generation of noxious intermediates (NO₂, N₂O₄). It is expected that this study would inspire the design of more artful photocatalysts for effective charge transfer and safe pollutants purification.

Electrochemical Study of Semiconductor Properties for Bismuth Silicate-Based Photocatalysts Obtained via Hydro-/Solvothermal Approach

Three bismuth silicate-based photocatalysts (composites of Bi₂SiO₅ and Bi₁₂SiO₂₀) prepared via the hydro-/solvothermal approach were studied using electrochemical methods. The characteristic parameters of semiconductors, such as flat band potential, donor density, and mobility of their charge carriers, were obtained and compared with the materials’ photocatalytic activity. An attempt was made to study the effect of solution components on the semiconductor/liquid interface (SLI). In particular, the Mott–Schottky characterization was made in a common model electrolyte (Na₂SO₄) and with the addition of glycerol as a model organic compound for photocatalysis. Thus, a medium close to those in photocatalytic experiments was simulated, at least within the limits allowed by electrochemical measurements. Zeta-potential measurements and electrochemical impedance spectroscopy were used to reveal the processes taking place at the SLI. It was found that the medium in which measurements were carried out dramatically impacted the results. The flat band potential values (E_fb) obtained via the Mott–Schottky technique were shown to differ significantly depending on the solution used in the experiment, which is explained by different processes taking place at the SLI. A strong influence of specific adsorption of commonly used sulfate ions and neutral molecules on the measured values of E_fb was shown.

Insights into thermally assisted photocatalytic overall water splitting over ZnTi-LDH in a gas–solid reaction system

H2O2 and bridge hydroxyl groups form because of water splitting. This process occurs intensely with the addition of heat, resulting in generation of more intermediates. Meanwhile, the separation of electrons and holes is accelerated by the heat.

In2S3/BiOI composites boost visible-light photocatalytic degradation of tetracycline hydrochloride

In₂S₃/BiOI composites have potential to degrade tetracycline hydrochloride under visible light due to the synergistic effect between In₂S₃ and BiOI.