Qin Chen

Acidic electrocatalytic CO₂ reduction (CO₂RR) to multicarbon (C₂₊) products offers a promising pathway for efficient carbon utilization, as acidic media suppress carbonate formation and improve CO₂ availability. However, two intrinsic limitations, rapid reduction of Cu⁺ to Cu⁰ and fast desorption/diffusion of the *CO intermediate, severely hindered C–C coupling and thus diminish ethylene (C₂H₄) selectivity in acidic CO₂RR. Here, we constructed a molecular cage on the Cu₂O surface by grafting cetyltrimethylammonium bromide (CTAB), which simultaneously stabilized Cu⁺ and restricted *CO diffusion, thereby enabling efficient CO₂-to-C₂H₄ conversion under strongly acidic conditions. Density functional theory calculations revealed that the molecular cage significantly increased local *CO coverage, which lowered the C–C coupling energy barrier while raising the energy barrier for hydrogen evolution reduction. In situ attenuated total reflection infrared spectroscopy demonstrated that CTAB-induced confinement strengthened *CO adsorption and slowed its surface diffusion, accelerating the C–C coupling kinetics. Furthermore, in situ X-ray adsorption near-edge structure confirmed that the molecular cage effectively prevented the reduction of Cu⁺ to metallic Cu, maintaining the active Cu⁺ species during operation. As a result, the optimized Cu₂O@CTAB catalyst delivered a high C₂H₄ Faradaic efficiency of 60% across 300–1100 mA cm^–2 in the strongly acidic electrolyte. Notably, it achieved a CO₂ single-pass utilization of 64.7%, an energy efficiency of 37.9%, and stable operation for over 195 h at 500 mA cm^–2 toward C₂₊ products. This work presents a generalizable molecular-cage strategy for overcoming intrinsic bottlenecks in acidic CO₂RR toward efficient C₂₊ product formation.

Summarized the optimization strategies for various high-performance catalyst materials to enhance the performance of PEC CO ₂ RR.

Hydrogen peroxide (H₂O₂) is an attractive green oxidant and energy carrier, but its industrial production remains energy- and resource-intensive. Photocatalytic synthesis from O₂ and H₂O offers a safer and more sustainable alternative, yet its efficiency is hampered by sluggish formation and rapid decomposition pathways. Here, we demonstrate a plasmon-engineered strategy to overcome both challenges using Au@TiO₂ core-shell nanostructures. The nanocubic Au@TiO₂ (NC@TiO₂) achieves a remarkable H₂O₂ production rate of 350.5 mM h^-1g^-1 under full-spectrum irradiation -1.6 times higher formation and 47% lower decomposition compared to bare TiO₂. Spectroscopic analysis and simulations reveal that localized surface plasmon resonance (LSPR) in the Au core orchestrates photocarrier dynamics: electrons generated in TiO₂ are funneled to Au sites to drive O₂ reduction, while plasmonic hot electrons neutralize TiO₂ holes that would otherwise decompose H₂O₂. The morphology dependence of this effect is evident: NC@TiO₂ with stronger LSPR outperforms rhombic dodecahedral Au@TiO₂. These results establish plasmon-mediated charge steering as a powerful tool to enhance both efficiency and selectivity in solar-to-chemical conversion, providing a design principle for next-generation photocatalysts.

Single-atom Ni catalysts hold great promise for the acidic CO₂ reduction reaction (CO₂RR), owing to their high CO selectivity. However, their performance under industrially relevant high current conditions is limited by the weak interaction between isolated Ni-N₄ sites and *COOH intermediates, restricting efficient CO₂ conversion. Here, we introduced edge-rich Ni-N₄ sites via support vacancy engineering to enhance *COOH adsorption, thereby boosting the CO₂RR activity and selectivity in acidic media. Density functional theory calculations revealed that edge-rich Ni-N₄ sites induced an upward shift in the Ni d-band center, leading to stronger *COOH binding and improved reaction kinetics. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images confirmed the uniform dispersion of single-atom Ni sites at the edge of the carbon support. X-ray adsorption spectroscopy further validated the successful anchoring of Ni-N₄ sites on the carbon nanotube matrix. Furthermore, in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy directly evidenced the enhanced *COOH binding on the engineered active sites. As a result, the optimized catalyst achieved a high CO faradaic efficiency exceeding 94.5% at 800 mA cm^-2, alongside a cathodic energy efficiency above 44.2% at pH = 1, suppressing previously reported benchmarks. This work establishes a versatile strategy for electronic structure modulation through edge-site engineering, offering a pathway to unlock the full potential of single-atom catalysts for the acidic CO₂RR at high current densities.

Electrocatalysis enables the conversion of CO₂ into value-added fuels and chemicals, offering a sustainable solution for greenhouse gas mitigation. However, achieving high selectivity for C2 products like ethylene (C₂H₄) remains challenging due to competing C1 pathways and complex multielectron processes. Here, we demonstrate that plasmon resonances can selectively enhance the electroreduction of CO₂ to C₂H₄ by 27.0% on a CuPd catalyst under LED illumination (625 nm) at -1.3 V_RHE. Photocurrent response, in situ FTIR spectroscopy, and COMSOL simulations reveal that plasmon-derived hot electrons and heating greatly facilitate *CO formation at the CuPd interface, which diffuses to the Cu surface for subsequent C-C coupling. DFT calculations show that the increased *CO coverage on the Cu sites reduces the energy barrier for C-C coupling, ultimately enhancing C₂H₄ generation. This work offers valuable mechanistic insights into plasmon-mediated electrocatalysis, guiding the development of more efficient plasmonic tandem electrocatalysts for future carbon recycling technologies.

Electrocatalytic CO₂ reduction into value‐added fuels and chemicals by renewable electric energy is one of the important strategies to address global energy shortage and carbon emission. Though the classical H‐type electrolytic cell can quickly screen high‐efficiency catalysts, the low current density and limited CO₂ mass transfer process essentially impede its industrial applications. The electrolytic cells based on electrolyte flow system (flow cells) have shown great potential for industrial devices, due to higher current density, improved local CO₂ concentration, and better mass transfer efficiency. The design and optimization of flow cells are of great significance to further accelerate the industrialization of electrocatalytic CO₂ reduction reaction (CO₂RR). In this review, the progress of flow cells for CO₂RR to C₂₊ products is concerned. Firstly, the main events in the development of the flow cells for CO₂RR are outlined. Second, the main design principles of CO₂RR to C₂₊ products, the architectures, and types of flow cells are summarized. Third, the main strategies for optimizing flow cells to generate C₂₊ products are reviewed in detail, including cathode, anode, ion exchange membrane, and electrolyte. Finally, the preliminary attempts, challenges, and the research prospects of flow cells for industrial CO₂RR toward C₂₊ products are discussed.