Visible-Light-Driven Overall Water Splitting Boosted by Tetrahedrally Coordinated Blende Cobalt(II) Oxide Atomic Layers

Local polarization redistribution in ZnmIn2S3+m for the enhancing synergetic piezo-photocatalytic overall water splitting

Piezo-photocatalytic water (deuterium oxide) decomposition is a promising strategy for realizing renewable energy, but the manipulation of the polar center remains a big challenge. This study uses a simple low-temperature hydrothermal process to successfully manufacture ZnmIn2Sm+3 (m = 1-3) (ZnIn2S4, Zn2In2S5 and Zn3In2S6). Incorporating both experimental and theoretical analyses, the structural contraction and local polarization of the Zn-S bond in Zn2In2S5 enhance the piezoelectric response and surface charge accumulation, which facilitate charge transfer and reduce the activation energy of water. Remarkably, Zn2In2S5 exhibits excellent piezoelectric photocatalytic total water splitting performance (H2/O2: 4284.72/1967.00 μmol g-1h-1), which is 1.77 times that of photocatalytic performance. Moreover, a significant enhancement in D2O splitting performance can be obtained for the optimized Zn2In2S5. Our work offers valuable insights into the disclosure of local polarization in catalysts for enhancing piezo-photocatalytic overall water splitting.

Continuous Strain Regulation of Palladium-Gold at the Atomic Level

Revealing the effect of surface structure changes on the electrocatalytic performance is beneficial to the development of highly efficient catalysts. However, precise regulation of the catalyst surface at the atomic level remains challenging. Here, we present a continuous strain regulation of palladium (Pd) on gold (Au) via a mechanically controllable surface strain (MCSS) setup. It is found that the structural changes induced by the strain setup can accelerate electron transfer at the solid-liquid interface, thus achieving a significantly improved performance toward hydrogen evolution reaction (HER). In situ X-ray diffraction (XRD) experiments further confirm that the enhanced activity is attributed to the increased interplanar spacing resulting from the applied strain. Theoretical calculations reveal that the tensile strain modulates the electronic structure of the Pd active sites and facilitates the desorption of the hydrogen intermediates. This work provides an effective approach for revealing the relationships between the electrocatalyst surface structure and catalytic activity.

Electrostatic interaction and surface S vacancies synergistically enhanced the photocatalytic degradation of ceftriaxone sodium

ZnIn₂S₄ ultrathin 2D nanosheets with a positive surface charge are synthesized by a hydrothermal method and different contents of surface S vacancies are induced via heat treatment of as-prepared ZnIn₂S₄ (ZIS). As the S vacancies contents increased, the photocatalytic degradation efficiency of ceftriaxone (CTRX) sodium is promoted. Especially, ZIS-300 shows the best degradation efficiency (88.8%) for an initial CTRX concentration of 10 mg L^-1 in 2 h. It is found that S vacancies cause the electron density of surface metal atoms (Zn, In) to be decreased, which makes the effective adsorption and activation of ceftriaxone anions through electrostatic adsorption interactions. Meanwhile, S vacancies also serve as active centers to promote the absorption of O₂ and gather electrons to form •O₂^- species. The photogenerated holes quickly transfer to the surface of the catalyst to directly degrade the adsorbed CTRX. Thus, the photocatalytic CTRX degradation efficiency is significantly improved. Finally, a possible mechanism for over defective ZIS is proposed. This work provides a feasible strategy for the efficient degradation of antibiotics from the perspective of electrostatic adsorption and molecule activation.

State-of-the-Art Advancements of Atomically Thin Two-Dimensional Photocatalysts for Energy Conversion

Excessive use of fossil fuels leads to energy shortages and environmental pollution, threatening human health and social development. As a clean, green, and sustainable technology, generation of renewable energy from...

Selective photocatalytic oxidation of cyclohexene coupled with hydrogen evolution from water splitting over Ni/NiO/CdS and mechanism insight

The reaction process of photocatalytic oxidation of cyclohexene including the oxidation products and oxidation active substance.

Controllable synthesis of Ni3S2@MOOH/NF (M = Fe, Ni, Cu, Mn and Co) hybrid structure for the efficient hydrogen evolution reaction

The design and synthesis of hybrid core-shell catalysts is of great significance for obtaining an excellent performance of hydrogen evolution reaction (HER). However, it remains a challenge to explore the exact active sites and research the catalytic mechanism for HER. Here, a series of Ni₃S₂@MOOH/NF (M = Fe, Ni, Cu, Mn and Co) hybrid structures is firstly in-site grown on Ni foam by the typical hydrothermal and electrodeposition methods. The Ni₃S₂@NiOOH/NF catalyst with a core-shell structure exhibits a relatively low overpotential of 79 mV for HER at a current density of 10 mA cm^-2, which is one of the best catalytic activities reported so far. Moreover, it also shows good stability in the long-term durability test. Various spectral analysis and density functional theory calculations demonstrate that NiOOH is favorable for the adsorption of water molecules, and the S atom at the interface between Ni₃S₂ and NiOOH is favorable for the adsorption of H intermediates, which strongly accelerates the HER process in alkaline solution. This work provides a general strategy for the synthesis of electrocatalytic materials, which can be used for efficient electrocatalytic water splitting reactions.

Self-Nanocavity-Confined Halogen Anions Boosting the High Selectivity of the Two-Electron Oxygen Reduction Pathway over Ni-Based MOFs

We present a strategy of self-nanocavity confinement for substantially boosting the superior electrochemical hydrogen peroxide (H₂O₂) selectivity for conductive metal-organic framework (MOF) materials. By using operando synchrotron radiation X-ray adsorption fine structure and Fourier transform infrared spectroscopy analyses, the dissociation of key *OOH intermediates during the oxygen reduction reaction (ORR) is effectively suppressed over the self-nanocavity-confined X-Ni MOF (X = F, Cl, Br, or I) catalysts, contributing to a favorable two-electron ORR pathway for highly efficient H₂O₂ production. As a result, the as-prepared Br-confined Ni MOF catalyst significantly promotes H₂O₂ selectivity up to 90% in an alkaline solution, evidently outperforming the pristine Ni MOF catalyst (40%). Moreover, a maximal faradic efficiency of 86% with a high cumulative H₂O₂ yield rate of 596 mmol g_catalyst^-1 h^-1 for electrochemical H₂O₂ generation is achieved by the Br-confined Ni MOF catalyst.

Ultralong NiSe nanowire anchored on graphene nanosheets for enhanced electrocatalytic performance of triiodide reduction

Like their higher-dimensional counterparts, nanowire structures possess desirable features for electrocatalysis applications. In this study, ultralong NiSe nanowires (of diameters 50-150 nm and length 20 μm) were successfully anchored onto graphene nanosheets (NiSe NW/RGO). The NiSe nanowires were coated with a thick (∼10 nm) disordered surface replete with active sites. Benefiting from the fast charge-transfer channels and plentiful electroactive sites on the NiSe nanowires, in synergy with the high electroactive surface and electrical conductivity of the graphene nanosheets, the optimized NiSe NW/RGO exhibited a remarkably higher electrocatalytic activity than NiSe nanowires and typical Pt counter-electrodes (CEs). NiSe NW/RGO also exhibited the low charge-transfer resistance of 1.64 Ω cm² and delivered a higher power conversion efficiency (PCE = 7.99%) than Pt CEs (PCE = 7.76%).

Amorphization-induced surface electronic states modulation of cobaltous oxide nanosheets for lithium-sulfur batteries

Lithium-sulfur batteries show great potential to achieve high-energy-density storage, but their long-term stability is still limited due to the shuttle effect caused by the dissolution of polysulfides into electrolyte. Herein, we report a strategy of significantly improving the polysulfides adsorption capability of cobaltous oxide by amorphization-induced surface electronic states modulation. The amorphous cobaltous oxide nanosheets as the cathode additives for lithium-sulfur batteries demonstrates the rate capability and cycling stability with an initial capacity of 1248.2 mAh g^-1 at 1 C and a substantial capacity retention of 1037.3 mAh g^-1 after 500 cycles. X-ray absorption spectroscopy analysis reveal that the coordination structures and symmetry of ligand field around Co atoms of cobaltous oxide nanosheets are notably changed after amorphization. Moreover, DFT studies further indicate that amorphization-induced re-distribution of d orbital makes more electrons occupy high energy level, thereby resulting in a high binding energy with polysulfides for favorable adsorption.

Regulating the adsorption behaviour of the polysulfide species is the key to achieving highly stable Li-S batteries. Here, the authors show that amorphization-induced redistribution of d orbitals enable CoO to be a favourable candidate for polysulfide adsorption and conversion.

Ordered Bicontinuous Mesoporous Polymeric Semiconductor Photocatalyst

Owning triply periodic minimal surfaces and three-dimensional (3D) interconnected pores, bicontinuous porous materials have drawn enormous attention due to their great academic interest and potential applications in many fields including energy and catalysis. However, their synthesis has remained a great challenge. Here, we demonstrate the synthesis of a bicontinuous porous organic semiconductor photocatalyst, which involves the preparation of SiO₂ with a shifted double diamond (DD) structure through solvent evaporation-induced self-assembly of a polystyrene-block-poly(ethylene oxide) diblock copolymer and tetraethyl orthosilicate, followed by SiO₂-templated self-condensation of melamine monomers in a vacuum. Strikingly, the resultant DD-structured graphitic carbon nitride (g-CN) possesses two sets of 3D continuous mesopores with a mean diameter of 14 nm, which afford a high specific surface area of 131 m² g^-1 and an optical band gap of 2.8 eV. Being a visible-light-driven photocatalyst, the bicontinuous mesoporous g-CN exhibits high catalytic activity for water splitting to generate H₂ (6831 μmol g^-1 h^-1) with excellent cycling stability. This study provides a protocol for the construction of ordered mesoporous materials containing 3D continuous channels, which holds promise for catalysis applications.

Highly efficient photocatalytic reduction of CO2 to CO using cobalt oxide-coated spherical mesoporous silica particles as catalysts

Hybrid catalysts that cobalt oxide nanoparticles immobilized on outside surfaces of spherical SBA-15 presented unexpected photocatalytic activity towards CO₂-to-CO conversion.