Integrating non-precious-metal cocatalyst Ni3N with g-C3N4 for enhanced photocatalytic H2 production in water under visible-light irradiation

Multicomponent nickel-molybdenum-tungsten-based nanorods for stable and efficient alkaline seawater splitting

The electrolysis of seawater for hydrogen production holds promise as a sustainable technology for energy generation. Developing water-splitting catalysts with low overpotential and stable operation in seawater is essential. In this study, we employed a hydrothermal method to synthesize NiMoWOX microrods (NiMoWOX@NF). Subsequently, an annealing process yielded a composite N-doped carbon-coated Ni3N/MoO2/WO2 nanorods (NC@Ni3N/MoO2/WO2@NF), preserving the ultrahigh-specific surface area of the original structure. A two-electrode electrolytic cell was assembled using NC@Ni3N/MoO2/WO2@NF as the cathode and NiMoWOX@NF as the anode, demonstrating exceptional performance in seawater splitting. The cell operated at a voltage of 1.51 V with a current density of 100 mA·cm-2 in an alkaline seawater solution. Furthermore, the NC@Ni3N/MoO2/WO2@NF || NiMoWOX@NF electrolytic cell exhibited remarkable stability, running continuously for over 120 h at a current of 1100 mA·cm-2 without any observable delay. These experimental results are corroborated by density functional theory calculations. The NC@Ni3N/MoO2/WO2@NF || NiMoWOX@NF electrolyzer emerges as a promising option for industrial-scale hydrogen production through seawater electrolysis.

Partial Sulphidation to Regulate Coordination Structure of Single Nickel Atoms on Graphitic Carbon Nitride for Efficient Solar H2 Evolution

To develop a non-precious highly efficient cocatalyst to replace Pt on graphitic carbon nitride (g-C₃ N₄ ) for solar H₂ production is great significant, but still remains a huge challenge. The emerging single-atom catalyst presents a promising strategy for developing highly efficient non-precious cocatalyst owing to its unique adjustability of local coordination environment and electronic structure. Herein, this work presents a facile approach to achieve single Ni sites (Ni₁ -N₂ S) with unique local coordination structure featuring one Ni atom coordinated with two nitrogen atoms and one sulfur atom, confirmed by high-angle annular dark-field scanning transmission electron microscopy, X-ray absorption spectroscopy, and density functional theory calculation. Thanks to the unique electron structure of Ni₁ -N₂ S sites, the 1095 µmol g^-1 h^-1 of high H₂ evolution rate with 4.1% of apparent quantum yield at 420 nm are achieved. This work paves a pathway for designing a highly efficient non-precious transition metal cocatalyst for photocatalytic H₂ evolution.

Nanoengineering of Catalysts for Enhanced Hydrogen Production

Hydrogen (H2) has emerged as a sustainable energy carrier capable of replacing/complementing the global carbon-based energy matrix. Although studies in this area have often focused on the fundamental understanding of catalytic processes and the demonstration of their activities towards different strategies, much effort is still needed to develop high-performance technologies and advanced materials to accomplish widespread utilization. The main goal of this review is to discuss the recent contributions in the H2 production field by employing nanomaterials with well-defined and controllable physicochemical features. Nanoengineering approaches at the sub-nano or atomic scale are especially interesting, as they allow us to unravel how activity varies as a function of these parameters (shape, size, composition, structure, electronic, and support interaction) and obtain insights into structure–performance relationships in the field of H2 production, allowing not only the optimization of performances but also enabling the rational design of nanocatalysts with desired activities and selectivity for H2 production. Herein, we start with a brief description of preparing such materials, emphasizing the importance of accomplishing the physicochemical control of nanostructures. The review finally culminates in the leading technologies for H2 production, identifying the promising applications of controlled nanomaterials.

Transition metal phosphide of nickel and cobalt-modified Zn0.5Cd0.5S for efficient photocatalytic hydrogen evolution with visible light irradiation

Three transition metal phosphating compounds (NiCoP, Ni2P and Co2P) were loaded on Zn0.5Cd0.5S respectively. Among them, the Zn0.5Cd0.5S/NiCoP composite photocatalyst has the best hydrogen evolution activity.

Disordered mesoporous carbon activated peroxydisulfate pretreatment facilitates disintegration of extracellular polymeric substances and anaerobic bioconversion of waste activated sludge

The potential of disordered mesoporous carbon (DMC) as catalyst of peroxydisulfate (PDS) to improve sludge solubilization and methane production was investigated. Results showed that DMC activated PDS (DMC/PDS) to produce sulfate radicals (SO₄^-), facilitating cells rupture and sludge matrix dissociation by degrading the carbonyl and amide groups in organic biopolymers (especially proteins, polysaccharides and humus). At the optimal DMC/PDS dosage of 0.04/1.2 g-mmol/g-VS, SCOD was increased from initial 294.0 to 681.5 mg/L, with the methane production rate of 12.6 mL/g-VS/day. Moreover, DMC could serve as electron mediator to accelerate electron transfer of microorganisms, building a more robust anaerobic metabolic environment. Modelling analysis further demonstrated the crucial role of DMC/PDS pretreatment in biological degradation and methane productivity. This study indicated that DMC/PDS pretreatment can prominently enhance the release of soluble substances and methane production, aiding the utilization of PDS oxidation technology for improving anaerobic bioconversion of sludge.

Metal-organic framework (MOF) composite materials for photocatalytic CO2 reduction under visible light

The tridentate ligand 2,4,6-tris(2-(pyridin-4-yl)vinyl)-1,3,5-triazine (TPVT) was designed and synthesized. We prepared metal-organic framework (TPVT-MOFs) crystals containing TPVT, 1,3,5-benzenetricarboxylic acid and cobalt by solvothermal reaction. Then, a series of composite materials with different contents of TPVT-MOFs were obtained by combining TPVT-MOFs with g-C3N4. Due to the interaction between TPVT-MOFs and g-C3N4, the composite materials have a more favorable valence band (VB) and conduction band (CB) for photocatalytic reduction of CO2 and oxidation of H2O. Under the conditions of visible light and a gas-solid system without a co-catalyst, a photosensitizer and a sacrificial agent, the yield of CO2 reduction by TPVT-MOFs@g-C3N4-10 can reach 56.4 μmol·g-1·h-1, which is 3.2 times that of pure g-C3N4 (17.5 μmol·g-1·h-1). The results of DFT calculations showed that the adsorption of H2O on the TPVT-MOFs@g-C3N4 composite material was more preferential, which promoted the adsorption and reduction of CO2.

Catching and killing of airborne SARS-CoV-2 to control spread of COVID-19 by a heated air disinfection system

Airborne transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) via air-conditioning systems poses a significant threat for the continued escalation of the current coronavirus disease (COVID-19) pandemic. Considering that SARS-CoV-2 cannot tolerate temperatures above 70 °C, here we designed and fabricated efficient filters based on heated nickel (Ni) foam to catch and kill SARS-CoV-2. Virus test results revealed that 99.8% of the aerosolized SARS-CoV-2 was caught and killed by a single pass through a novel Ni-foam-based filter when heated up to 200 °C. In addition, the same filter was also used to catch and kill 99.9% of Bacillus anthracis, an airborne spore. This study paves the way for preventing transmission of SARS-CoV-2 and other highly infectious airborne agents in closed environments.

New Core-Shell Hybrid Material IR-MOF3@COF-LZU1 for Highly Efficient Visible-Light Photocatalyst Degrading Nitroaromatic Explosives

Nitroaromatic explosives in wastewater are hardly degraded, which seriously endangers the ecological environment and human safety. We report a core-shell structure hybrid material (IR-MOF3@COF-LZU1) with high crystallinity and graded porosity. It is an effective visible-light-driven photocatalyst that degrades p-nitrophenol (PNP). After 3.5 h, PNP was degraded well under visible light, and it is proven that the photocatalytic degradation is efficient. In addition, this photocatalytic activity adhered to pseudo-first-order kinetics, and a possible photocatalytic mechanism was discussed in detail.

Nickel-decorated g-C3N4 hollow spheres as an efficient photocatalyst for hydrogen evolution and oxidation of amines to imines

Photocatalysts composed of earth-abundant elements are highly desired for photocatalytic hydrogen evolution as well as oxidation of amines to imines without the requirement of precious metals.

Fabrication of a novel Ni3N/Ni4N heterojunction as a non-noble metal co-catalyst to boost the H2 evolution efficiency of Zn0.5Cd0.5S

Ni_xN/Zn_0.5Cd_0.5S composites displayed better photocatalytic hydrogen production from water in comparison with pristine Zn_0.5Cd_0.5S (ZCS), as well as Pt/ZCS and Ni₃N/ZCS.

Interfaces of graphitic carbon nitride-based composite photocatalysts

This review concentrates on the interface issues of g-C₃N₄-based photocatalysts, including methods for constructing interfaces, techniques for identifying interfaces, and the types and roles of the as-developed interfaces.