Targeted Regulation of the Electronic States of Nickel Toward the Efficient Electrosynthesis of Benzonitrile and Hydrogen Production

Beyond Traditional Synthesis: Electrochemical Approaches to Amine Oxidation for Nitriles and Imines

The electrochemical oxidation of amines to nitriles and imines represents a critical frontier in organic electrochemistry, offering a sustainable pathway to these valuable compounds. Nitriles and amines are pivotal in various industrial applications, including pharmaceuticals, agrochemicals, and materials science. This review encapsulates the recent advancements in the electrooxidation process, emphasizing mechanistic understanding, electrode material innovations, optimization of reaction conditions, and exploration of solvent and electrolyte systems. Additionally, the review addresses the operational parameters that significantly affect the electrooxidation process, such as current density, temperature, and electrode surface, offering insights into their optimization for enhanced performance. By providing a comprehensive view of the current state and prospects of amine electrooxidation to nitriles and imines, this review aims to inspire further development, innovation, and research in this promising area of green chemistry.

Unlocking Efficient Hydrogen Production: Nucleophilic Oxidation Reactions Coupled with Water Splitting

Electrocatalytic water splitting driven by sustainable energy is a clean and promising water-chemical fuel conversion technology for the production of high-purity green hydrogen. However, the sluggish kinetics of anodic oxygen evolution reaction (OER) pose challenges for large-scale hydrogen production, limiting its efficiency and safety. Recently, the anodic OER has been replaced by a nucleophilic oxidation reaction (NOR) with biomass as the substrate and coupled with a hydrogen evolution reaction (HER), which has attracted great interest. Anode NOR offers faster kinetics, generates high-value products, and reduces energy consumption. By coupling NOR with hydrogen evolution reaction, hydrogen production efficiency can be enhanced while yielding high-value oxidation products or degrading pollutants. Therefore, NOR-coupled HER hydrogen production is another new green electrolytic hydrogen production strategy after electrolytic water hydrogen production, which is of great significance for realizing sustainable energy development and global decarbonization. This review explores the potential of nucleophilic oxidation reactions as an alternative to OER and delves into NOR mechanisms, guiding future research in NOR-coupled hydrogen production. It assesses different NOR-coupled production methods, analyzing reaction pathways and catalyst effects. Furthermore, it evaluates the role of electrolyzers in industrialized NOR-coupled hydrogen production and discusses future prospects and challenges. This comprehensive review aims to advance efficient and economical large-scale hydrogen production.

Recent Advancements in Electrochemical Hydrogen Production via Hybrid Water Splitting

As one of the most promising approaches to producing high-purity hydrogen (H2 ), electrochemical water splitting powered by the renewable energy sources such as solar, wind, and hydroelectric power has attracted considerable interest over the past decade. However, the water electrolysis process is seriously hampered by the sluggish electrode reaction kinetics, especially the four-electron oxygen evolution reaction at the anode side, which induces a high reaction overpotential. Currently, the emerging hybrid electrochemical water splitting strategy is proposed by integrating thermodynamically favorable electro-oxidation reactions with hydrogen evolution reaction at the cathode, providing a new opportunity for energy-efficient H2 production. To achieve highly efficient and cost-effective hybrid water splitting toward large-scale practical H2 production, much work has been continuously done to exploit the alternative anodic oxidation reactions and cutting-edge electrocatalysts. This review will focus on recent developments on electrochemical H2 production coupled with alternative oxidation reactions, including the choice of anodic substrates, the investigation on electrocatalytic materials, and the deep understanding of the underlying reaction mechanisms. Finally, some insights into the scientific challenges now standing in the way of future advancement of the hybrid water electrolysis technique are shared, in the hope of inspiring further innovative efforts in this rapidly growing field.

Interfacial Micro-Environment of Electrocatalysis and Its Applications for Organic Electro-Oxidation Reaction

Conventional designing principal of electrocatalyst is focused on the electronic structure tuning, on which effectively promotes the electrocatalysis. However, as a typical kind of electrode-electrolyte interface reaction, the electrocatalysis performance is also closely dependent on the electrocatalyst interfacial micro-environment (IME), including pH, reactant concentration, electric field, surface geometry structure, hydrophilicity/hydrophobicity, etc. Recently, organic electro-oxidation reaction (OEOR), which simultaneously reduces the anodic polarization potential and produces value-added chemicals, has emerged as a competitive alternative to oxygen evolution reaction, and the role IME played in OEOR is receiving great interest. Thus, this article provides a timely review on IME and its applications toward OEOR. In this review, the IME for conventional gas-involving reactions, as a contrast, is first presented, and then the recent progresses of IME toward diverse typical OEOR are summarized; especially, some representative works are thoroughly discussed. Additionally, cutting-edge analytical methods and characterization techniques are introduced to comprehensively understand the role IME played in OEOR. In the last section, perspectives and challenges of IME regulation for OEOR are shared.

Mo-Ni-based Heterojunction with Fine-customized d-Band Centers for Hydrogen Production Coupled with Benzylamine Electrooxidation in Low Alkaline Medium

Benzylamine electrooxidation reaction (BAOR) is a promising route to produce value-added, easy-separated benzonitrile, and effectively hoist H2 production. However, achieving excellent performance in low alkaline medium is a huge challenge. The performance is intimately correlated with effective coupling of HER and BAOR, which can be achieved by manipulating the d-electron structure of catalyst to regulate the active species from water. Herein, we constructed a biphasic Mo0.8 Ni0.2 N-Ni3 N heterojunction for enhanced bifunctional performance toward HER coupled with BAOR by customizing the d-band centers. Experimental and theoretical calculations indicate that charge transfer in the heterojunction causes the upshift of the d-band centers, which one side facilitates to decrease water activation energy and optimize H* adsorption on Mo0.8 Ni0.2 N for promoting HER activity, the other side favors to more easily produce and adsorb OH* from water for forming NiOOH on Ni3 N and optimizing adsorption energy of benzylamine, thus catalyzing BAOR effectively. Accordingly, it shows an industrial current density of 220 mA cm-2 at 1.59 V and high Faradaic efficiencies (>99 %) for H2 production and converting benzylamine to benzonitrile in 0.1 M KOH/0.5 M Na2 SO4 . This work guides the design of excellent bifunctional electrocatalysts for the scalable production of green hydrogen and value-added products.

Upgrading Organic Compounds through the Coupling of Electrooxidation with Hydrogen Evolution

The electrocatalytic splitting of water is recognized to be the most sustainable and clean technology for the production of hydrogen (H2 ). Unfortunately, the efficiency is seriously restricted by the sluggish kinetics of the oxygen evolution reaction (OER) at the anode. In contrast to the OER, the electrooxidation of organic compounds (EOO) is more thermodynamically and kinetically favorable. Thus, the coupling of the EOO and hydrogen evolution reaction (HER) has emerged as an alternative route, as it can greatly improve the catalytic efficiency for the production of H2 . Simultaneously, value-added organic compounds can be generated on the anode through electrooxidation upgrading. In this Minireview, we highlight the latest progress and milestones in coupling the EOO with the HER. Emphasis is focused on the design of the anode catalyst, understanding the reaction mechanism, and the construction of the electrolyzer. Moreover, challenges and prospects are offered relating to the future development of this emerging technology.