Shuifen Xie

Now a new generation of electrocatalysts featuring the coexistence of single atoms (SAs) and metal clusters/nanoparticles (CLs/NPs) are exhibiting remarkable synergistic effects for alkaline hydrogen evolution reaction (HER). The distinct chemical environments of SAs and CLs/NPs allow for the spatial separation of different reaction steps, boosting alkaline HER synergistically. This review provides a comprehensive account of the advanced SAs‐CLs/NPs synergistic electrocatalysts for alkaline HER and anion exchange membrane water electrolysis (AEMWE). We classify these catalysts into four types based on the elemental composition of the active sites and discuss their respective synthetic approaches, with an emphasis on strategies to control the relative loading and spatial proximity of SAs and CLs/NPs. We then present a detailed mechanistic discussion of how synergistic interactions between SAs and CLs/NPs accelerate alkaline HER kinetics, drawing on insights from in situ/operando spectral characterization techniques and density functional theory (DFT) calculations. The performance of these catalysts in AEMWE devices is also evaluated, highlighting the most promising systems for practical application. Finally, we outline the key challenges that must be overcome to realize the full potential of SAs‐CLs/NPs synergistic catalysts.

Ferroelectric semiconductors hold considerable promise for photothermal catalytic CO2 hydrogenation to high-value hydrocarbons, owing to their intrinsic polarization electric field that facilitates charge separation. However, their practical performance is severely limited by weak bulk polarization, rapid carrier recombination at high temperatures, insufficient surface active sites, and poor C–C coupling efficiency. Herein, we report a lanthanum (La)-mediated bulk–surface synergistic strategy to engineer ferroelectric BaTiO3 (BTO) for highly selective photothermal CO2 hydrogenation to C2H4. A series of La2O3@BaTi1–xLaxO3–δ (x%-BTLO) composites were fabricated via a one-pot hydrothermal method. La doping induces lattice expansion along the [001] polar axis, which significantly strengthens the bulk polarization electric field, raises the Curie temperature above 200 °C, and promotes charge delocalization through orbital hybridization, thereby suppressing bulk carrier recombination under photothermal conditions. Meanwhile, the surface-decorated La2O3 nanoparticles form a tight heterojunction with the La-doped BaTi1–xLaxO3–δ substrate, which accelerates interfacial charge transfer and provides active sites for boosting C–C coupling. Consequently, the optimized 10%-BTLO catalyst exhibits a C2H4 yield of 5.88 mmol·g–1·h–1 with a selectivity of 79.7% at 200 °C and shows long-term stability over 120 h. This work establishes a feasible bulk–surface synergistic design principle for ferroelectric catalysts and offers a pathway to achieve efficient and selective photothermal conversion of CO2 into high-value C2 + products.

The CO ₂ electroreduction reaction (CO ₂ RR) in acidic media offers a promising route to convert renewable electricity into value‐added chemicals with high carbon utilization, yet its selectivity is severely limited by competing hydrogen evolution reaction. Despite extensive investigations into cation effects in acidic CO ₂ RR, the role of anions remains underexplored. Here, we systematically investigate the effect of three common electrolyte anions—Cl ⁻ , SO ₄ ²⁻ , and H ₂ PO ₄ ⁻ —on acidic CO ₂ RR. Theoretical studies suggest that Cl ⁻ induces the most negative surface charge on Cu relative to SO ₄ ²⁻ and H ₂ PO ₄ ⁻ , which enhances C–C coupling and thereby improves selectivity toward C ₂₊ products. Electrochemical evaluation shows that Cu catalysts in Cl ⁻ ‐containing electrolytes deliver the highest C ₂₊ selectivity, surpassing those in SO ₄ ²⁻ and H ₂ PO ₄ ⁻ environments. Specifically, we achieve a peak C ₂₊ Faradaic efficiency of 82% at 300 mA cm ⁻² . The promotional role of Cl ⁻ is further observed on Ag catalysts in acidic CO ₂ RR. In situ Raman spectroscopy reveals that Cl ⁻ enhances the adsorption of *CO intermediates on Cu surfaces, thereby promoting C–C coupling and C ₂₊ product generation. This work reports an effective anion electrolyte engineering strategy to enhance CO ₂ RR performance under acidic conditions.

Acidic electrochemical CO₂ reduction reaction (CO₂RR) offers an attractive route to store intermittent renewables as valuable chemicals with high carbon efficiency but suffers from low selectivity due to predominant hydrogen evolution reaction. Utilizing concentrated alkali cations steers the acidic CO₂RR to multicarbon (C₂₊) products but leads to salt precipitation. Here we report a molecular tuning strategy to facilitate acidic CO₂RR to ethylene under a low K⁺ concentration by modifying tetraphenylporphyrin-based molecules onto a Cu surface. At 200 mA cm^-2, we achieve a record ethylene Faradaic efficiency (FE) of 53% on 5,10,15,20-tetraphenyl-21H,23H-porphine zinc functionalized Cu catalysts (a 1.2× improvement compared to the best reports at above 100 mA cm^-2 under an acidic electrolyte having a low alkali cation concentration) and a high C₂₊ FE of 85%, as well as a high CO₂ single-pass utilization of 72%. This work presents a catalyst design strategy for efficient acidic CO₂-to-ethylene electrolysis under low alkali-cation availability.

Amorphous surfaces, which offer greater tunability compared to their crystalline counterparts, are increasingly recognized as highly active yet unstable phases for specific electrocatalysis reactions under harsh conditions. Whereas successfully creating and stabilizing amorphous surfaces on low‐dimensional electrocatalysts remains a significant challenge. This work elaborately synthesizes ultrathin crystalline/amorphous Pt@RuIrO _x core–shell nanowires that effectively overcome the trade‐off among activity, stability, and cost for acidic oxygen evolution reaction (OER) catalysts in proton exchange membrane (PEM) water electrolysis. An in situ oxidation process actualizes the confinement of subnanometer amorphous Ir‐doped RuO _x overlayers on ultrathin Pt nanowires. Heteroatom Ir‐doping induces amorphization of host RuO _x and effectively modulates the electronic structure and Ru─O covalency. The Pt@RuIrO _x nanowires exhibit a substantially intensified robustness when serving as OER active electrocatalysts, demonstrating an ultralow overpotential (146 mV) at 10 mA cm ⁻² and a remarkable stability. In a practical PEM water electrolyzer, the catalyst requires only 1.55 V cell voltage at 1.0 A cm ⁻² and maintains long‐lasting operation for over 2000 h. Mechanistic studies validate that the flexible amorphous surface vitalizes the coexistence of multiple reaction pathways, along with an unprecedented lattice oxygen self‐healing capability. These findings establish surface amorphous phase engineering as a powerful strategy for designing high‐performance electrocatalysts.