Accelerating Anode Reaction with Electro-oxidation of Alcohols over Ru Nanoparticles to Reduce the Potential for Water Splitting

Oxygen Atom Migration Dominates Anomalous Reversible Oxidation of Ru Nanosheets

Oxidation is a ubiquitous reaction in nature. For most metals (especially metal nanoparticles [NPs]), they will be completely oxidized under suitable conditions, except ruthenium (Ru). In this work, in situ transmission electron microscopy (in situ TEM) and ex situ spectroscopy were employed to investigate the oxidation process of Ru nanosheets. Ex situ spectroscopic analysis demonstrates the incomplete oxidation of Ru nanosheets to RuO₂, while the in situ TEM observations uncover an anomalous reverse phase transformation from the oxidized to metallic phase during oxidation. Combined with theoretical calculations, the oxygen atom migration dominates the reversible oxidation process, strikingly distinct from the unidirectional oxidation pathways in conventional metallic systems. The as-generated abundant Ru─RuO2 heterointerfaces formed through reversible oxidation provide a wealth of active sites for electrochemical alkaline hydrogen evolution reaction (HER). Herein, the study not only lays a foundation for the understanding complex dynamic oxidation processes, but also offers new insights into the design of nanocatalysts.

Unilamellar MnO2 nanosheets confined Ru-clusters combined with pulse electrocatalysis for biomass electrooxidation in neutral electrolytes

The electrochemical oxidation of 5-hydroxymethylfurfural (HMFOR) in alkaline electrolyte is a promising strategy for producing high-value chemicals from biomass derivatives. However, the disproportionation of aldehyde groups under strong alkaline conditions and the polymerization of HMF to form humic substances can impact the purity of 2,5-furandicarboxylic acid (FDCA) products. The use of neutral electrolytes offers an alternative environment for electrolysis, but the lack of OH- ions in the electrolyte often leads to low current density and low yields of FDCA. In this study, a sandwich-structured catalyst, consisting of Ru clusters confined between unilamellar MnO2 nanosheets (S-Ru/MnO2), was used in conjunction with an electrochemical pulse method to realize the electrochemical conversion of 5-hydroxymethylfurfural into FDCA in neutral electrolytes. Pulse electrolysis and the strong electron transfer between Ru clusters and MnO2 nanosheets help maintain Ru in a low oxidation state, ensuring high activity. The increased *OH generation led to a groundbreaking current density of 47 mA/cm2 at 1.55 V vs. reversible hydrogen electrode (RHE) and an outstanding yield rate of 98.7% for FDCA in a neutral electrolyte. This work provides a strategy that combines electrocatalyst design with an electrolysis technique to achieve remarkable performance in neutral HMFOR.

Visible-Light-Enhanced Hydrogen Evolution through Anodic Furfural Electro-Oxidation Using Nickel Atomically Dispersed Copper Nanoparticles

A novel copper nanoparticle variant, denoted as Cu98Ni2 NPs, which incorporate Ni atoms in an atomically dispersed manner, has been successfully synthesized via a straightforward one-pot electrochemical codeposition process. These nanoparticles were subsequently employed as an anode to facilitate the oxidation of furfural, leading to the production of hydrogen gas. Voltammetric measurements revealed that the inclusion of trace amounts of Ni atoms in the nanoparticles resulted in a pronounced synergistic electronic effect between Cu and Ni. Consequently, a 43% increase in current density at 0.1 V was observed in comparison to pure Cu NPs. Importantly, when the Cu98Ni2 NPs were irradiated with visible light, a remarkable current density enhancement factor of 505% at 0.1 V was achieved relative to that of pure Cu NPs in the absence of light. This enhancement can be attributed to localized surface plasmon resonance induced by visible light, which triggers photothermal and photoelectric effects. These effects collectively contribute to the significant overall improvement in the electrocatalytic oxidation of furfural, leading to enhanced hydrogen evolution.