Earth-abundant electrocatalysts are desirable for the efficient and selective reduction of CO2 to value-added chemicals. Here, a low-cost porous Zn electrocatalyst is synthesized using a facile electrodeposition method to boost the performance of CO2 electrocatalytic reaction (CO2RR). In an H-cell reactor, the porous Zn catalyst can convert CO2 to CO at a remarkably high faradaic efficiency (FE, ~95%) and current density (27 mA cm–2) at –0.95 V versus the reversible hydrogen electrode. Detailed electrokinetic studies demonstrate that instead of the enhanced intrinsic activity, the dramatically increased active sites play a decisive role in improving the catalytic activity. In addition, the high local pH induced by the highly porous structure of Zn results in enhanced CO selectivity due to the suppressed H2 evolution. Furthermore, we present a straightforward strategy to transform the porous Zn electrode into a gas diffusion electrode. This way, the CO2RR current density can be boosted to 200 mA cm–2 with ~84% FE for CO at –0.64 V in a flow-cell reactor, which is, to date, the best performance observed over non-noble CO2RR catalysts.

The single-layer graphene film, when incorporated with molecular-sized pores, is predicted to be the ultimate membrane. However, the major bottlenecks have been the crack-free transfer of large-area graphene on a porous support, and the incorporation of molecular-sized nanopores. Herein, we report a nanoporous-carbon-assisted transfer technique, yielding a relatively large area (1 mm²), crack-free, suspended graphene film. Gas-sieving (H₂/CH₄ selectivity up to 25) is observed from the intrinsic defects generated during the chemical-vapor deposition of graphene. Despite the ultralow porosity of 0.025%, an attractive H₂ permeance (up to 4.1 × 10⁻⁷ mol m⁻² s⁻¹ Pa⁻¹) is observed. Finally, we report ozone functionalization-based etching and pore-modification chemistry to etch hydrogen-selective pores, and to shrink the pore-size, improving H₂ permeance (up to 300%) and H₂/CH₄ selectivity (up to 150%). Overall, the scalable transfer, etching, and functionalization methods developed herein are expected to bring nanoporous graphene membranes a step closer to reality.

The activity and selectivity of the electrochemical CO₂ reduction reaction (CO₂RR) are often hindered by the limited access of CO₂ to the catalyst surface and overtaken by the competing hydrogen evolution reaction. Herein, it is revealed that polymers used as catalyst binders can effectively modulate the accessibility of CO₂ relative to H₂O at the vicinity of the catalyst and thus the performance of CO₂RR. Three polymers with different hydrophilicities (i.e., polyacrylic acid (PAA), Nafion, and fluorinated ethylene propylene (FEP)) are selected as binders for Cu catalysts. At a thickness of only ≈1.2 nm, these binders strongly affect the activity and selectivity toward multi‐carbon (C₂₊) products. The FEP coated catalyst exhibits a C₂₊ partial current density of over 600 mA cm⁻² with ≈77% faradaic efficiency at −0.76 V versus RHE. This high performance is attributed to the hydrophobic (aerophilic) properties of FEP, which reduces the local concentration of H₂O and enhances that of the reactant (i.e., CO₂) and the reaction intermediates (i.e., CO). These findings suggest that tuning the hydrophobicity of electrocatalysts with polymer binders can be a promising way to regulate the performance of electrochemical reactions involving gas–solid–liquid interfaces.