Preparation of S- scheme heterojunction Bi28O32 (SO4)10/NiAl LDH for efficient photocatalytic degradation of tetracycline

At present, the construction of high-efficiency photocatalytic degradation system of antibiotic pollutants has become a research hotspot. In this paper, Bi₂₈O₃₂(SO₄)₁₀/NiAl LDH photocatalyst with three-dimensional spherical morphology was successfully prepared by hydrothermal method followed by calcination, thus applying to the degradation of tetracycline. The characterization and photochemical analysis of the resulted material were used to determine the type of formed heterojunction. Bi₂₈O₃₂(SO₄)₁₀ and NiAl LDH build a close contact interface. The matching band gap structure makes S-scheme heterojunction formed between the two single component. Benefited from this structure, the Bi₂₈O₃₂(SO₄)₁₀/NiAl LDH composite with the mass ratio of 1:1 exhibited 95% efficiency in degradation of tetracycline after irradiation for 120 min, and it is stable, reusable and universal. The apparent rate constant of TC degradation by heterojunction catalyst is greatly increased, which is 5.35 and 4.91 times that of Bi₂₈O₃₂(SO₄)₁₀ and NiAl LDH. Overall, this paper provides a way of thinking for the design of new bismuth based photocatalytic materials, and thus providing a reference for the rational design of S-scheme heterojunction.     

Aboundent oxygen defects in CoFe-LDH derivatives for enhanced photo-thermal synergistic catalytic hydrogen production from NaBH4

Two-dimensional catalysts, which are sensitive to visible light and have a photothermal effect, can be used to catalyse the release of H₂ from sodium borohydride (NaBH₄) are being actively explored in energy saving systems. In this work, oxygen vacancy enriched two-dimensional CoFe-layered double hydroxide (CoFe-LDH) derivatives (named as CoFe-x °C, x = 200–500) have been explored for NaBH₄ hydrolysis catalyzed by photo-thermal synergy without external heat source. The CoFe-300 °C presents its initial hexagonal lamellar structure and has the highest concentration of oxygen vacancy. These unique properties guarantee its excellent photo-thermal synergistic catalytic performance, achieving hydrogen production rate of 1877.5 mmol g⁻¹ h⁻¹, and maintains high efficiency after 5 cycles. This enhanced photo-thermal synergistic catalytic mechanism is the •OH (generated from h⁺ and H₂O) attacks BH₄⁻ (absorbed on O_v sites) to produce H₂, the heat from photothermal conversion accelerates the adsorption ability and attacking rate. This study opens a new strategy for the synergistic photo-thermal catalytic hydrolysis of NaBH₄.     

Synergistically modulating the electronic structure of Cr-doped FeNi LDH nanoarrays by O-vacancy and coupling of MXene for enhanced oxygen evolution reaction

Water splitting is an environmentally friendly method of hydrogen generation. However, it is severely limited by the slow anodic oxygen evolution reaction (OER). Iron-nickel layered double hydroxides (FeNi LDH) are promising electrocatalysts for OER, but their intrinsically low electrical conductivity and activity limit the practical applications. Herein, chromium-doped FeNi LDH nanoarrays in situ vertically grown on the surface of the Ti₃C₂T_x MXene (Cr-FeNi LDH/MXene) are successfully synthesized. Remarkably, the robust interaction and electrical coupling between Cr–FeNi LDH and MXene, as well as conspicuous charge transfer and the oxygen vacancies optimizing the adsorption free energy of intermediates, equip the nanocomposites with brilliant catalytic activity and stability toward OER. Thus, the optimized Cr–FeNi LDH/MXene shows a considerable boost in the OER, which affords low overpotential (232 mV at 10 mA cm^?2) and excellent durability. This work offers a new path to designing highly efficient and earth-abundant catalysts for water splitting and beyond.