Facile and Scalable Synthesis of Self-Supported Zn-Doped CuO Nanosheet Arrays for Efficient Nitrate Reduction to Ammonium

Exploration of Multidimensional Structural Optimization and Regulation Mechanisms: Catalysts and Reaction Environments in Electrochemical Ammonia Synthesis

Ammonia (NH3) is esteemed for its attributes as a carbon-neutral fuel and hydrogen storage material, due to its high energy density, abundant hydrogen content, and notably higher liquefaction temperature in comparison to hydrogen gas. The primary method for the synthetic generation of NH3 is the Haber-Bosch process, involving rigorous conditions and resulting in significant global energy consumption and carbon dioxide emissions. To tackle energy and environmental challenges, the exploration of innovative green and sustainable technologies for NH3 synthesis is imperative. Rapid advances in electrochemical technology have created fresh prospects for researchers in the realm of environmentally friendly NH3 synthesis. Nevertheless, the intricate intermediate products and sluggish kinetics in the reactions impede the progress of green electrochemical NH3 synthesis (EAS) technologies. To improve the activity and selectivity of the EAS, which encompasses the electrocatalytic reduction of nitrogen gas, nitrate, and nitric oxide, numerous electrocatalysts and design strategies have been meticulously investigated. Here, this review primarily delves into recent progress and obstacles in EAS pathways, examining methods to boost the yield rate and current efficiency of NH3 synthesis via multidimensional structural optimization, while also exploring the challenges and outlook for EAS.

Spatially confined synthesis of large-sized MoS2nanosheets in molten KSCN toward efficient hydrogen evolution

Low-temperature KSCN molten salt is a promising technique to synthesize defect-rich MoS2catalysts for hydrogen evolution reaction (HER). However, owing to the fast ion diffusion rate for rapid crystal growth, the resultant catalysts show a morphology of microsphere, which aggregates from MoS2nanosheets, to suppress the catalytic performance. In this work, large-sized few-layer MoS2nanosheets are synthesized via a spatial confinement strategy by adding inert NaCl into the KSCN molten salt. With the NaCl spacer to physically block the long-distance ion diffusion and isolate the chemical reaction, the MoS2nucleation and subsequent crystal growth could be controlled, guiding the nanosheets to grow along the narrow gap between the NaCl crystals to avoid aggregation. As a result, ultrathin MoS2nanosheets with a large geometry size are constructed. Profiting from the architecture to expose active sites and boost charge transfer kinetics, the large-sized few-layer MoS2nanosheets exhibit an impressive HER performance, showing a smallη10of 160 mV and a low Tafel slope of 53 mV dec-1with excellent stability. This work provides not only an efficient HER catalyst but also a facile spatial confinement technique to design and synthesize a large spectrum of transition metal sulfides for broad uses.

Copper-based electro-catalytic nitrate reduction to ammonia from water: Mechanism, preparation, and research directions

Global water bodies are increasingly imperiled by nitrate pollution, primarily originating from industrial waste, agricultural runoffs, and urban sewage. This escalating environmental crisis challenges traditional water treatment paradigms and necessitates innovative solutions. Electro-catalysis, especially utilizing copper-based catalysts, known for their efficiency, cost-effectiveness, and eco-friendliness, offer a promising avenue for the electro-catalytic reduction of nitrate to ammonia. In this review, we systematically consolidate current research on diverse copper-based catalysts, including pure Cu, Cu alloys, oxides, single-atom entities, and composites. Furthermore, we assess their catalytic performance, operational mechanisms, and future research directions to find effective, long-term solutions to water purification and ammonia synthesis. Electro-catalysis technology shows the potential in mitigating nitrate pollution and has strategic importance in sustainable environmental management. As to the application, challenges regarding complexity of the real water, the scale-up of the commerical catalysts, and the efficient collection of produced NH3 are still exist. Following reseraches of catalyst specially on long term stability and in situ mechanisms are proposed.

Integrated Gradient Cu Current Collector Enables Bottom-Up Li Growth for Li Metal Anodes: Role of Interfacial Structure

3D Cu current collectors have been demonstrated to improve the cycling stability of Li metal anodes, however, the role of their interfacial structure for Li deposition pattern has not been investigated thoroughly. Herein, a series of 3D integrated gradient Cu-based current collectors are fabricated by the electrochemical growth of CuO nanowire arrays on Cu foil (CuO@Cu), where their interfacial structures can be readily controlled by modulating the dispersities of the nanowire arrays. It is found that the interfacial structures constructed by sparse and dense dispersion of CuO nanowire arrays are both disadvantageous for the nucleation and deposition of Li metal, consequently fast dendrite growth. In contrast, a uniform and appropriate dispersity of CuO nanowire arrays enables stable bottom Li nucleation associated with smooth lateral deposition, affording the ideal bottom-up Li growth pattern. The optimized CuO@Cu-Li electrodes exhibit a highly reversible Li cycling including a coulombic efficiency of up to ≈99% after 150 cycles and a long-term lifespan of over 1200 h. When coupling with LiFePO4 cathode, the coin and pouch full-cells deliver outstanding cycling stability and rate capability. This work provides a new insight to design the gradient Cu current collectors toward high-performance Li metal anodes.