Jianfang Zhang

The electrocatalytic nitrate reduction reaction (NO ₃ ⁻ RR) provides an effective route for removing NO ₃ ⁻ from wastewater and converting it to valuable ammonia (NH ₃ ).

Electrochemical CO₂ reduction reaction can be used to produce value‐added hydrocarbon fuels and chemicals by coupling with clean electrical energy. However, highly active, selective, and energy‐efficient CO₂ conversion to multicarbon hydrocarbons, such as C₂H₄, remains challenging because of the lack of efficient catalysts. Herein, an ultrasonication‐assisted electrodeposition strategy to synthesize CuO nanosheets for low‐overpotential CO₂ electroreduction to C₂H₄ is reported. A high C₂H₄ Faradaic efficiency of 62.5% is achieved over the CuO nanosheets at a small potential of −0.52 V versus a reversible hydrogen electrode, corresponding to a record high half‐cell cathodic energy efficiency of 41%. The selectivity toward C₂H₄ is maintained for over 60 h of continuous operation. The CuO nanosheets are prone to in situ restructuring during CO₂ reduction, forming abundant grain boundaries (GBs). Stable Cu⁺/Cu⁰ interfaces are derived from the low‐coordinated Cu atoms in the reconstructed GB regions and act as highly active sites for CO₂ reduction at low overpotentials. In situ Raman spectroscopic analysis and density functional theory computation reveal that the Cu⁺/Cu⁰ interfaces offer high *CO surface coverage and lower the activation energy barrier for *CO dimerization, which, in synergy, facilitates CO₂ reduction to C₂H₄ at low overpotentials.

Regulating the selectivity toward a target hydrocarbon product is still the focus of CO₂ electroreduction. Here, we discover that the original surface Cu species in Cu gas‐diffusion electrodes plays a more important role than the surface roughness, local pH, and facet in governing the selectivity toward C₁ or C₂ hydrocarbons. The selectivity toward C₂H₄ progressively increases, while CH₄ decreases steadily upon lowering the Cu oxidation species fraction. At a relatively low electrodeposition voltage of 1.5 V, the Cu gas‐diffusion electrode with the highest Cu^δ+/Cu⁰ ratio favors the pathways of hydrogenation to form CH₄ with maximum Faradaic efficiency of 65.4% and partial current density of 228 mA cm⁻² at −0.83 V vs RHE. At 2.0 V, the Cu gas‐diffusion electrode with the lowest Cu^δ+/Cu⁰ ratio prefers C–C coupling to form C₂₊ products with Faradaic efficiency topping 80.1% at −0.75 V vs RHE, where the Faradaic efficiency of C₂H₄ accounts for 46.4% and the partial current density of C₂H₄ achieves 279 mA cm⁻². This work demonstrates that the selectivity from CH₄ to C₂H₄ is switchable by tuning surface Cu species composition of Cu gas‐diffusion electrodes.

In situ reconstruction of two-dimensional defects in CuO nanowires improves adsorption strength of *CO intermediates and *CO surface coverage, leading to high activity and selectivity of CO₂ electroreduction to C₂H₄.

Electrocatalytic nitrogen reduction reaction (NRR) is a complementary route to the traditional Haber‐Bosch process. Boosting the reaction kinetics of electrocatalytic NRR is key to promote the NH₃ yield. Herein, we demonstrate that the confinement of reactive intermediates (e. g., *N₂) in highly ordered blue TiO₂ nanotubes (b‐TiO₂) can significantly enhance the surface reaction rate of electrocatalytic NRR on the encapsulated metal oxide catalysts. The enhancement of the reaction rate of NH₃ synthesis is attributed to the increased surface coverage of intermediates inside the b‐TiO₂ nanotubes. Benefiting from the confinement effect of intermediates, the b‐TiO₂ nanotubes enclosing metal oxide electrodes show both higher production rate and Faradaic efficiency of NH₃ than the combined ones of individual metal oxide and b‐TiO₂ electrodes.

High-performance noble metal-free electrocatalysts are extremely desired for overall water splitting, but there are huge challenges. Herein, we report a novel one-step electrochemical anodic oxidation and cathodic deposition strategy to in situ fabricate three-dimensional coral-like Ni₃S₂ on Ni foam (NF) for electrocatalytic overall water splitting. In a typical two-electrode cell, NF acts as both cathodic and anodic electrodes with thiourea aqueous solution as the electrolyte. The nickel ions from the anodic oxidation of NF are directly used as nickel sources to form 3D coral-like Ni₃S₂/NF by the cathodic deposition method simultaneously. The optimal 3D Ni₃S₂/NF-4 electrode shows high electrocatalytic activity for hydrogen evolution reaction and oxygen evolution reaction with low overpotentials of 89 and 242 mV, respectively, to afford 10 mA cm^–2. When the as-obtained Ni₃S₂/NF-4 is used as a bifunctional electrocatalyst in an electrolyzer, a low applied voltage of 1.577 V is needed to reach 10 mA cm^–2, with extremely long durability. This work focuses on the rational design of unique structures as efficient non-noble metal-based electrocatalysts, which hold great potential for practical applications in electrocatalytic water splitting.