The active site engineering of electrocatalysts, as one of the most economical and technological approaches, is a promising strategy to enhance the intrinsic activity and selectivity towards electrochemical CO₂ reduction reaction. Herein, an indium-based porphyrin framework (In-TCPP) with a well-defined structure, highly dispersed catalytic center, and good stability was constructed for efficient CO₂-to-formate conversion. In-TCPP could achieve a high Faraday efficiency for formate (90%) and a cathodic energy efficiency of 63.8% in flow cells. In situ attenuated total reflectance Fourier transform infrared spectroscopy and density functional theory calculation confirm that the crucial intermediate is *COOH species which contributes to the formation of formate. This work is expected to provide novel insights into the precise design of active sites for high-performance electrocatalysts towards electrochemical CO₂ reduction reaction.

Covalent organic frameworks (COFs) represent an emerging class of crystalline porous polymers with high porosity, good stability, and adjustable structure, and their excellent characteristics lay a solid foundation for electrocatalysis. This review systematically introduces the design principles of the catalytic sites in two-dimensional (2D) COF-based electrocatalysts and analyzes the relationship between 2D COF structure and their electrocatalytic performances. In particular, the recent progress in the field of 2D COFs as electrocatalysts is comprehensively summarized. Finally, we discuss the current shortcomings and challenges on tailoring 2D COF for high-performance electrocatalysts in details, and look forward to promoting more researches on 2D COF-based electrocatalysts.

Accurate researches on the surface plasmon resonance (SPR)-based applications of chiral plasmonic metal nanoparticles (NPs) still remain a great challenge. Herein, a series of chiral plasmonic metal NPs, e.g., chiral Au nanorods (c-Au NRs), c-Au@Ag core–shell, and c-Au@TiO₂ core–shell NRs, with different chiroptical activities have been produced. Plasmonic circular dichroism (PCD) bands of c-Au NRs can be precisely tailored by tuning the longitudinal SPR (LSPR) and amount of Au NRs as seeds. Besides, a shift of PCD bands within ultraviolet–visible–near infrared ray (UV–vis–NIR) region can also be achieved through the functionalization of a shell of another metal or semiconductor. Interestingly, chirality transfer from c-Au core to Ag shell leads to new PCD bands at the near-UV region. The tuning of PCD bands and chirality transfer are confirmed by our developed theoretical model. Developing chiral Au NRs-based chiral plasmonic nanomaterials with tunable chiroptical activities will be helpful to understand the structure-direct PCD and to extend circularly polarized-based applications.

Rational design and synthesis of multimetallic nanostructures (NSs) are fundamentally important for electrochemical CO₂ reduction reaction (CO₂RR). Herein, a multi-step seed-mediated growth method is applied to synthesize asymmetric AuAgCu heterostructures using Au nanobipyramids as nucleation seeds, in which their composition and structures are well controlled. We find that the selectivity of C₂ products for CO₂RR could be effectively regulated by tandem catalysis and electronic effect over trimetallic AuAgCu heterostructures. Particularly, the Faraday efficiency toward ethanol could reach up to 37.5% at a potential of −0.8 V versus reversible hydrogen electrode over asymmetric Au₁Ag₁Cu₅ heterostructures with segregated domains of three constituent metals. This work provides an efficient strategy for the synthesis of multicomponent architectures to boost their promising application in CO₂RR.

Electrochemical CO₂ reduction reaction (CO₂RR) is an attractive pathway for closing the anthropogenic carbon cycle and storing intermittent renewable energy by converting CO₂ to valuable chemicals and fuels. The production of highly reduced carbon compounds beyond CO and formate, such as hydrocarbon and oxygenate products with higher energy density, is particularly desirable for practical applications. However, the productivity towards highly reduced chemicals is typically limited by high overpotential and poor selectivity due to the multiple electron-proton transfer steps. Tandem catalysis, which is extensively utilized by nature for producing biological macromolecules with multiple enzymes via coupled reaction steps, represents a promising strategy for enhancing the CO₂RR performance. Improving the efficiency of CO₂RR via tandem catalysis has recently emerged as an exciting research frontier and achieved significant advances. Here we describe the general principles and also considerations for designing tandem catalysis for CO₂RR. Recent advances in constructing tandem catalysts, mainly including bimetallic alloy nanostructures, bimetallic heterostructures, bimetallic core-shell nanostructures, bimetallic mixture catalysts, metal-metal organic framework (MOF) and metal-metallic complexes, metal-nonmetal hybrid nanomaterials and copper-free hybrid nanomaterials for boosting the CO₂RR performance are systematically summarized. The study of tandem catalysis for CO₂RR is still at the early stage, and future research challenges and opportunities are also discussed.