Interface engineering: Synergism between S-scheme heterojunctions and Mo-O bonds for promote photocatalytic hydrogen evolution

Tailoring Advanced CdS Anisotropy-Driven Charge Spatial Vectorial Separation and Migration via In Situ Dual Co-Catalyst Synergistic Layout

Tailoring advanced anisotropy-driven efficient separation and migration of photogenerated carriers is a pivotal stride toward enhancing photocatalytic activity. Here, CdS-MoS2 binary photocatalysts are tailored into a dumbbell shape by leveraging the rod-shaped morphology of CdS and employing an in situ tip-induction strategy. To further enhance the photocatalytic activity, an in situ photo-deposition strategy is incorporated to cultivate MnOx particles on the dumbbell-shaped CdS-MoS2. The in situ deposition of MnOx effectively isolated the oxidatively active sites on the CdS surface, emphasizing the reductively active crystalline face of CdS, specifically the (002) face. Benefiting from its robust activity as a reduction active site, MoS2 adeptly captures photogenerated electrons, facilitating the reduction of H+ to produce hydrogen. The anisotropically driven separation of CdS photogenerated carriers markedly mitigates the Coulomb force or binding force of the photogenerated electrons, thus promoting a smoother migration toward the active site for photocatalytic hydrogen evolution. The hydrogen evolution rate of 35MnOx-CdS-MoS2-3 surpasses that of CdS by nearly an order of magnitude, achieving a quantum efficiency of 22.30% at 450 nm. Under simulated solar irradiation, it attains a rate of 42.86 mmol g-1 h-1. This work imparts valuable insights for the design of dual co-catalysts, anisotropy-driven spatial vectorial charge separation and migration, and the analysis of migration pathways of photogenerated carriers.

Reinforcing the Adsorption and Conversion of Polysulfides in Li-S Battery by Incorporating Molybdenum into MnS/MnO Nanorods

The Sabatier principle suggests that an excessive adsorption of lithium polysulfides (LiPSs) by metal compounds may hinder their conversion in the absence of a conversion module. Therefore, it is imperative to establish a synergetic effect mechanism between "strong adsorption" and "rapid conversion" for LiPSs. To achieve this coexistence, a molybdenum-doped MnS/MnO@C porous structure is designed as a multifunctional coating on the polypropylene (PP) separator. The incorporation of MnS/MnO@C enhances the adsorption capacity towards LiPSs, while molybdenum facilitates subsequent conversion. Benefiting from the synergistic effect of each component and its large specific surface area, the cell with Mo-doped MnS/MnO@C coating achieves smooth adsorption-diffusion-conversion processes and exhibits an appreciable rate performance with outstanding cycling stability. Even when sulfur loading increases to 9.68 mg cm-2 , the modified battery delivers an excellent initial areal capacity of 11.69 mAh cm-2 and maintains 6.97 mAh cm-2 after 50 cycles at 0.1 C. This study presents a promising approach to simultaneously accomplish "strong adsorption" and "rapid conversion" of polysulfides, offering novel perspectives for devising dual-functional modified separators.

Exposed {110} facets of BiOBr anchored to marigold-like MnCo2O4 with abundant interfacial electron transfer bridges and efficient activation of peroxymonosulfate

Precise charge transfer modification and efficient activation of peroxymonosulfate are effective methods for increasing photocatalytic efficiency. Here, BiOBr/MnCo2O4 photocatalysts with abundant Mn-Br bonds were generated by immobilizing the exposed {110} facets of BiOBr in the marigold-like MnCo2O4. The prepared BiOBr/MnCo2O4 retained the marigold-like morphology of MnCo2O4 while exhibiting good adsorption properties and interface contact effects. More importantly, the interfacial Mn-Br bond between MnCo2O4 and BiOBr functioned as charge transport bridges, allowing for a directional transfer channel and lowering the potential energy barrier for interfacial charge transfer. In addition, the exposure of the {110} facets exhibited more Mn atom-anchored sites for easy anchoring of BiOBr, significantly solving the stability problem of the bismuth material. Compared to MnCo2O4 + BiOBr, which did not form Mn-Br bonds, the MnCo2O4/BiOBr heterojunction had more efficient photocatalytic activity (1.3 times) and stability. This suggested that using electronic bridges for directional charge transfer was an efficient way to improve photocatalytic efficiency.

Tailoring Spin State of Perovskite Oxides by Fluorine Atom Doping for Efficient Oxygen Electrocatalysis

Promoting the initially deficient but economical catalysts to high-performing competitors is important for developing superior catalysts. Unlike traditional nano-morphology construction methods, this work focuses on intrinsic catalytic activity enhancement via heteroatom doping strategies to induce lattice distortion and optimize spin-dependent orbital interaction to alter charge transfer between catalysts and reactants. Experimentally, a series of different concentrations of fluorine-doped lanthanum cobaltate (F_x -LaCoO₃ ) exhibiting excellent electrocatalytic activity is synthesized, including a low overpotential of 390 mV at j = 10 mA cm^-2 for OER and a large half-wave potential of 0.68 V for ORR. Meanwhile, the assembled rechargeable Zn-air batteries deliver an excellent performance with a large specific capacity of 811 mAh/g_Zn under 10 mA cm^-2 and stability of charge/recharge (120 h). Theoretically, taking advantage of density functional theory calculations, it is found that the prominent OER/ORR performance arises from the spin state transition of Co³⁺ (Low spin state (LS, t_2g ⁶ e_g ⁰ ) → Intermediate spin state (IS, t_2g ⁵ e_g ¹ ) and the mediated d-band center upshift by F atom incorporation. This work establishes a novel avenue for designing superior electrocatalysts in perovskite-based oxides by regulating spin states.

Recent Progress in Halide Perovskite Nanocrystals for Photocatalytic Hydrogen Evolution

Due to its environmental cleanliness and high energy density, hydrogen has been deemed as a promising alternative to traditional fossil fuels. Photocatalytic water-splitting using semiconductor materials is a good prospect for hydrogen production in terms of renewable solar energy utilization. In recent years, halide perovskite nanocrystals (NCs) are emerging as a new class of fascinating nanomaterial for light harvesting and photocatalytic applications. This is due to their appealing optoelectronic properties, such as optimal band gaps, high absorption coefficient, high carrier mobility, long carrier diffusion length, etc. In this review, recent progress in halide perovskite NCs for photocatalytic hydrogen evolution is summarized. Emphasis is given to the current strategies that enhance the photocatalytic hydrogen production performance of halide perovskite NCs. Some scientific challenges and perspectives for halide perovskite photocatalysts are also proposed and discussed. It is anticipated that this review will provide valuable references for the future development of halide perovskite-based photocatalysts used in highly efficient hydrogen evolution.

Novel scheme towards interfacial charge transfer between ZnIn2S4 and BiOBr for efficient photocatalytic removal of organics and chromium (VI) from water

Construction of Z-scheme heterostructure is an effective strategy to enhance the charge carriers' separation. However, successfully achieving this on the defect heterojunction to improve the photocatalytic activity remains challenging. This work successfully obtained sulfur vacancy in the ZnIn₂S₄/BiOBr (SZIS/BOB) heterojunction composites with S-O covalent bonding using a hydrothermal method. As a result, they exhibited superior photocatalytic and stability performance. The optimized SZIS/BOB-10 exhibited excellent rhodamine B degradation (95.2%) and chromium (VI) reduction (97.8%) within 100 min under visible light. The enhanced composites with S-vacancies, S-O bond, and internal electric field induced the Z-scheme charge transfer mechanism. We had verified this mechanism based on the surface photovoltage spectra, electron spin response spectra, and density functional theory calculations. This work not only provides valuable insights into designing photocatalysts with a direct Z scheme heterostructure but also delineates a promising strategy for developing efficient photocatalysts to degrade organic pollutants.

Surface-Induced Engineering: P-Induced Formation of Surface Bonding States Based on the ZIF Synthesis Strategy for Photocatalytic Hydrogen Evolution

The development of clean energy is one of the effective strategies to solve carbon peak and carbon neutrality. The severe recombination of photogenerated carriers is one of the fundamental reasons that hinder the development of photocatalysis. In this work, NiCo-MOF/ZIF was obtained by the "ZIF on MOF" strategy for the first time, and a stable bonding state of surface P(δ^-)-Co/Ni(δ⁺)-O(δ^-) was formed on the surface of the catalyst by a one-step oxidation-phosphorus doping strategy. The X-ray photoelectron spectroscopy technique proves that phosphorus doping forms a unique bonding state on the surface of CoO-NiO. The novel surface bonding state can effectively inhibit the recombination of photogenerated carriers and can increase the migration rate of photogenerated electrons, which accelerates the process of photocatalytic hydrogen evolution. Photocatalytic hydrogen evolution kinetics verifies that the formation of P(δ^-)-Co/Ni(δ⁺)-O(δ^-) bonding states can accelerate the process of photocatalytic hydrogen evolution, and the durability of the catalyst is verified by cycling experiments. This work provides a new strategy for catalyst synthesis, new horizons, and effective strategies for the surface design of catalysts and the development of photocatalytic hydrogen evolution.