Jianxing Shen

Electrocatalytic oxidation of biomass-derived platform molecules represents a pivotal strategy for chemical production and reducing reliance on fossil resources. Among various biomass-derived platforms, 5-(hydroxymethyl)furfural (HMF) stands out as one of the most promising candidates. Its oxidation products are widely used in polymer monomers, biofuels, pharmaceutical intermediates, and fine chemicals. This review provides a comprehensive overview of the electrocatalytic conversion of HMF into high-value 2,5-furandicarboxylic acid (FDCA). We systematically elaborate on the reaction pathways and fundamental mechanisms of HMF electrooxidation (HMFOR), summarize the advances in characterization technologies and electrocatalyst design, and evaluate the current toward industrial deployment of HMFOR. Particular attention is devoted to the indispensable roles of in situ techniques in capturing real-time reaction kinetics, as well as the contributions of density functional theory (DFT), molecular dynamics (MD) simulations, and artificial intelligence (AI) in promoting mechanistic understanding and directing rational catalyst development. Finally, the existing bottlenecks and future research directions are critically proposed. We anticipate that this review will not only deepen the fundamental mechanistic insights into HMFOR but also propose practical and universal design principles for constructing highly active and selective electrocatalysts, thereby accelerating the large-scale implementation and commercialization of biomass electrorefining technologies.

Ammonia (NH₃) is one of the hydrogen carriers that has received extensive attention due to its high hydrogen content and carbon-free nature. The ammonia electro-oxidation reaction (AOR) and the liquid AOR (LAOR) are integral parts of an ammonia-based energy system. The exploration of low-cost and efficient electrocatalysts for the AOR and LAOR is very important but very difficult. In this work, a novel self-supporting AOR and LAOR bifunctional electrocatalyst of a Ag₃CuS₂ film is synthesized by a simple hydrothermal method. The Ag₃CuS₂ film without a substrate shows efficient catalytic activity and enhanced stability for NH₃ electrolysis in both aqueous ammonia solution and liquid ammonia, including an onset potential of 0.7 V for the AOR and an onset potential of 0.4 V for the LAOR. The density functional theory calculations prove that compared to Cu atoms, Ag atoms with appropriate charge density on the surface of Ag₃CuS₂ are more electrocatalytically active for NH₃ splitting, including the low energy barrier in the rate-determining *NH₃ dehydrogenation step and the spontaneous tendency in the N₂ desorption process. Overall, the foamed Ag₃CuS₂ film is one of prospective low-cost and stable electrocatalysts for the AOR and LAOR, and the self-supporting strategy without a substrate provides more perspectives to tailor more meaningful and powerful electrocatalysts.

Lewis acid–base theory and DFT results showed that different enrichment degrees of B and N elements in BCN can improve the adsorption energy of OH*/H₂O. BCN exhibits optimum electrocatalytic overall water splitting performance after adjustments.

Developing a scalable approach to construct efficient and multifunctional electrodes for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) is an urgent need for overall water splitting and zinc–air batteries. In this work, a freestanding 3D heterostructure film is synthesized from a Ni‐centered metal−organic framework (MOF)/graphene oxide. During the pyrolysis process, 1D carbon nanotubes formed from the MOF link with the 2D reduced graphene oxide sheets to stitch the 3D freestanding film. The results of the experiments and theoretical calculations show that the synergistic effect of the N‐doped carbon shell and Ni nanoparticles leads to an optimized film with excellent electrocatalytic activity. Low overpotentials of 95 and 260 mV are merely needed for HER and OER, respectively, to reach a current density of 10 mA cm⁻². In addition, a high half‐wave potential of 0.875 V is obtained for the ORR, which is comparable to that of Pt/RuO₂ and ranks among the top of non‐noble‐metal catalysts. The use of an “all‐in‐one” film as the electrode leads to excellent performance of the homemade water electrolyzer and zinc–air battery, indicating the potential of the film for practical applications.

As a class of highly stable materials, the application of high dielectric constant materials in the field of energy is hampered by their low electrical conductivity and poor energy storage capacity. To solve these inherent limitations, herein, a useful strategy was developed to improve the energy storage performance of high dielectric constant electrode materials by combining the characteristics of parallel-plate capacitors. A novel sandwich structure with a carbon fiber/metal oxide/metal oxynitride layer (CMM) were used to construct a “mini parallel-plate capacitor” in the electrode, and the capacitance was remarkably enhanced. In this structure, the metal oxides (SnO₂, Fe₂O₃, VO₂, and TiO₂) with different dielectric constants worked as the dielectric, while the carbon fiber and the metal oxynitride layer worked as the plate electrodes. As expected, the dielectric constant of the metal oxides was directly proportional to the capacitance increase. Specifically, the capacitance of TiO₂ was enhanced up to 11.75 times after the construction of this structure. Moreover, the relevant mechanism of the enhanced capacitance was investigated by the parallel-plate capacitor model. This novel strategy can provide new ideas for the study of high dielectric constant materials in the field of energy storage.

Sodium super ionic conductor (NASICON) Na₃V₂(PO₄)₃ (NVP) is a type of promising cathode material for sodium-ion batteries (SIBs) with superior structural integrity, high energy density, and fast diffusion of sodium ions. However, NVP suffers from intrinsically low electrical conductivity, which results in poor rate performance. Herein, we report on the outstanding cathode performance of Na₃V₂(PO₄)₃ ([email protected]) wrapped by the ZIF-67-derived carbon, which was prepared by sol–gel method and solid-phase method. Electrochemical measurements show an initial discharge-specific capacity of 135 mA h g^–1 at 1 C, and the discharge capacity maintains 82 mA h g^–1 after 1000 cycles at 10 C. The results indicate the improvement in electrical conductivity and electrochemical performance due to the Co doping from ZIF-67. Moreover, we calculate the diffusion coefficient of sodium ions by the cyclic voltammetry (CV, D_Na⁺ = 1.521 × 10^–11 and 2.3484 × 10^–11 cm² s^–1 for charging and discharging, respectively) and the galvanostatic intermittent titration technique (GITT, D_Na⁺ ranges from 10^–11–10^–15 cm² s^–1). The exceptional performance is ascribed to the excellent structural stability and outstanding electrical conductivity of NVP modified by porous carbon skeleton and ZIF-67-derived carbon.

A thin vanadium–nickel oxynitride (VNiON) layer is synthesized on the corresponding oxide nanosheet surfaces. Such a material exhibits enhanced neutral NRR activity with an ammonia yield of ∼6.78 μg h⁻¹ cm_cat.⁻² and FE of ∼5.57%.