Yunqing Zhu

A potential-modulation strategy constructs spike-array Pd–Cu/Cu ₂ O nanostructures, whose tip-enhanced effect enables efficient nitrate conversion, achieving 100% conversion, 100% N ₂ selectivity, and excellent durability.

Electrocatalytic nitrate reduction (eNO₃RR) has gained widespread application as a green and efficient technique for ammonia synthesis. However, the accumulation of nitrite (NO₂^-) during the electrochemical reduction process significantly hampers the efficiency of converting nitrate (NO₃^-) into ammonia (NH₃). In this study, a Cu-MOF/Co-MOF@NF composite catalyst was developed on a nickel foam substrate using a hydrothermal method. The catalyst is composed of interconnected Cu-MOF@NF and Co-MOF@NF nanosheets, forming a flower-like nanostructure. X-ray photoelectron spectroscopy (XPS) reveals there is an electronic transfer between copper (Cu) and cobalt (Co) sites at the interface of Cu-MOF/Co-MOF@NF, thereby accelerating both the adsorption and reduction of NO₃^- at Cu sites and enhancing selective conversion to NH₃ at Co sites. At a potential of - 0.5 V vs RHE, the Cu-MOF/Co-MOF@NF exhibits a NO₃^- conversion to NH₃ that surpasses those of the Cu-MOF@NF and Co-MOF@NF by 8.5 and 39.6%, respectively, achieving NH₃ selectivity and yield of 93.3% and 318.5 μg·h^-1·cm^-2. In addition, Cu-MOF/Co-MOF@NF possesses exceptional catalytic activity and durability. Electron Paramagnetic Resonance (EPR) experiments reveal a significant amount of *H generated at the cathode interface. In-situ differential electrochemical mass spectrometry (DEMS) detection shows that the reduction pathway for NO₃^- over the Cu-MOF/Co-MOF@NF is as follows: *NO₃^- → *NO₂^- → *NO → *N → *NH → *NH₂ → *NH₃.

In this study, Ir nanoclusters adorned with abundant p-mercaptobenzoic acid (p-MBA) ligands were employed to fabricate an electrocatalytic material consisting of Ir nanoclusters embedded within two-dimensional Co-MOF nanosheets (Ir NCs@Co-MOF) for the electrocatalytic NO₃^- reduction reaction (NO₃^-RR). TEM analysis confirmed that Ir nanoclusters are uniformly distributed in 2D Co-MOF nanosheets, with an average diameter of about 1.8 nm. At a potential of -0.8 V vs RHE, the Ir NCs@Co-MOF catalyst achieved a nitrate conversion rate, ammonia selectivity, and yield of 92.5, 81.4%, and 230.1 μg·h^-1·cm^-2, respectively, over a reaction duration of 120 min. The strong interaction between Ir nanoclusters and Co-MOF serves to enhance electrocatalytic activity and accelerate the rate of nitrate reduction. Stability tests indicated that after 20 cycles, both the nitrate conversion and ammonia selectivity of the Ir NCs@Co-MOF catalyst demonstrated relative stability, thereby indicating a robust performance for this catalytic system. The results of EPR and TBA quenching experiments indicate that *H plays a key role in the NO₃^-RR process. In situ DEMS investigations revealed that during the NO₃^-RR process, the reaction pathway was as follows: *NO₃ → *NO₂ → *NO → *NOH → *NH₂OH → *NH₂ → *NH₃ → NH₃.

Currently, the electrochemical reduction of carbon dioxide faces significant challenges, including poor selectivity for C₂ products and low conversion efficiency. An effective strategy for optimizing the reduction reaction pathway and enhancing catalytic performance involves manipulating highly unsaturated atomic sites on the catalyst’s surface, thereby increasing the number of active sites. In this study, we employed sodium dodecylbenzenesulfonate (SDBS) as a surfactant in the electrodeposition method to synthesize copper cubes encapsulated with an amorphous shell (100 nm–250 nm) containing numerous defect sites on its surface. The electrocatalytic CO₂ reduction reactions in an H-type reactor showed that, compared to ED-Cu synthesized without additives, AS (amorphous shell)-Cu-5 exhibited a Faradaic efficiency value for ethylene that was 1.7 times greater than that of ED-Cu while significantly decreasing the Faradaic efficiency of hydrogen production. In situ attenuated total reflectance surface-enhanced infrared spectroscopy (ATR-SEIRAS) revealed that introducing an amorphous shell and abundant defects altered both the intermediate species and reaction pathways on the AS-Cu-5 catalyst’s surface, favoring C₂H₄ formation. The density functional theory (DFT) calculations further confirmed that amorphous copper lowers the energy barrier required for C-C coupling, resulting in a marked enhancement in FE-C₂H₄. Therefore, additive-assisted electrodeposition presents a simple and rapid synthesis method for improving ethylene selectivity in copper catalysts.

The treatment of nanofiltration concentrate has always been a critical technical challenge in the application of membrane technology for landfill leachate treatment. This study attempts to address this challenge using electrocatalytic oxidation technology. A Pt‐modified Ti/RuO ₂ ‐IrO ₂ anode was synthesized using a solution method. The results show that Pt was uniformly dispersed within the Ru‐Ir composite oxide phase, and Pt doping induced the formation of numerous disordered and mismatched lattices on the electrode coating surface. The interaction between Pt and the RuO ₂ ‐IrO ₂ system can enhance the stability of the ternary composite electrode, improve electron transport efficiency, and reduce surface resistance of the electrode coating, thereby increasing the efficiency of chemical reactions. In the treatment of nanofiltration concentrate of landfill leachate, it was found that under conditions of a current density of 20 mA·cm ⁻² , electrode distance of 0.5 cm, and pH = 5, the removal rates of COD, TOC, and NH ₄ ⁺ ‐N were 93.5%, 46%, and 98% respectively, with an energy consumption of only 0.66 kWh·(kg TOC) ⁻¹ . After 20 repeated experiments, the Ti/RuO ₂ ‐IrO ₂ ‐Pt 8% anode also demonstrated good stability and catalytic activity.

Covalent organic frameworks (COFs)-based nanoreactors have attracted broad interest in many fields due to their void-confinement effects. However, the inherent drawback of conventional nanoreactors is the lack of internal active sites, which limits their widespread utilization. Herein, we report the construction of hierarchical COF (EB-TFP) nanoreactor with pre-synthesized polyoxometalates (POM, [PV₂W₁₀O₄₀]⁵⁻ (PV₂W₁₀)) clusters encapsulated inside of COF (POM@COF). PV₂W₁₀@EB-TFP anchors nucleophilic-group (Br⁻ ions) and PV₂W₁₀ anion cluster within the COF framework via electrostatic interactions, which not only simplifies the reaction system but also enhances catalytic efficiency. The reaction performance of the PV₂W₁₀@EB-TFP nanoreactor can be tuned to achieve excellent catalytic activity in CO₂ cycloaddition reaction (CCR) for ∼ 97.63% conversion and ∼ 100% selectivity under visible light irradiation. A mechanistic study based on density functional theory (DFT) calculations and in-situ characterization was also carried out. In summary, we have reported a method for achieving the uniform dispersion of POM single clusters into COF nanoreactor, demonstrating the potential of POM@COF nanoreactor for synergistic photothermal catalytic CO₂ cycloaddition.

In this study, the performance of a zero-gap flow-through reactor with three-dimensional (3D) porous Ti/RuO₂-TiO₂@Pt anodes was systematically investigated for the electrocatalytic oxidation of phenolic wastewater, considering phenol and 4-nitrophenol (4-NP) as the target pollutants. The optimum parameters for the electrochemical oxidation of phenol and 4-NP were examined. For phenol degradation, at an initial concentration of 50 mg/L, initial pH of 7, NaCl concentration of 10.0 g/L, current density of 10 mA/cm², and retention time of 30 min, the degradation efficiency achieved was 95.05%, with an energy consumption of 15.39 kWh/kg; meanwhile, for 4-NP, the degradation efficiency was 98.42% and energy consumption was 19.21 kWh/kg (at an initial concentration of 40 mg/L, initial pH of 3, NaCl concentration of 10.0 g/L, current density of 10 mA/cm², and retention time of 30 min). The electrocatalytic oxidation of phenol and 4-NP conformed to the pseudo-first-order kinetics model, and the k values were 0.2562 min⁻¹ and 0.1736 min⁻¹, respectively, which are 1.7 and 3.6-times higher than those of a conventional electrolyzer. Liquid chromatography–mass spectrometry (LC–MS) was used to verify the intermediates formed during the degradation of phenol or 4-NP and a possible degradation pathway was provided. The extremely narrow electrode distance and the flow-through configuration of the zero-gap flow-through reactor were thought to be essential for its lower energy consumption and higher mass transfer efficiency. The zero-gap flow-through reactor with a novel 3D porous Ti/RuO₂-TiO₂@Pt electrode is a superior alternative for the treatment of industrial wastewater.