Electrochemical CO₂ reduction reaction through utilizing renewable electricity under mild conditions is a promising pathway toward achieving carbon neutrality. In this work, we designed a tubular graphyne functionalized with isolated Co single atom and lowered the activation energy barrier of its rate-determining step to as low as 0.46 eV. The catalytic performance was systematically evaluated through density functional theory calculations. Compared with the planar graphyne functionalized with isolated Co single atom, the tubular one not only significantly improves the utilization efficiency of Co single atoms by exposing them more thoroughly, but also increases the catalytic activity of Co single atom by enhancing electron density of states at the Fermi level, which causes a higher level of activation state for the adsorbed CO₂ molecules. Furthermore, it brought about the CO₂-to-CH₄ reduction reaction pathway, resulting in remarkable catalytic activity and high methane selectivity. Our study demonstrates the efficacy of curvature engineering in enhancing the intrinsic activity of single-atom catalysts, offering a novel strategy for designing advanced carbon cycle catalysts.

Catalytic CO₂ reduction reaction (CO₂RR) offers a promising approach for converting CO₂ into value-added chemicals and fuels. However, its practical development remains limited by unfavorable reaction energetics, competition from the hydrogen evolution reaction (HER), and complex product selectivity. Conventional catalyst regulation strategies predominantly rely on static structural design, whereas magnetic regulation introduces an additional degree of freedom through intrinsic spin-state engineering or external magnetic fields. This review systematically summarizes the recent research progress in magnetic regulation of CO₂RR with emphasis on the links among spin states, spin-resolved electronic structures, intermediate adsorption, reaction thermodynamics, product selectivity, competing reactions, and charge-carrier dynamics. Importantly, catalytic changes induced by an external magnetic field are not automatically equivalent to spin-mediated effects because magnetohydrodynamic transport, Lorentz-force-driven mass transfer, thermal perturbations, and interfacial transport can also contribute. The review therefore discusses both intrinsic magnetic regulation and field-induced effects while highlighting the evidence required to distinguish spin-associated mechanisms from non-spin contributions, including direct magnetic or spin characterization, spectroscopic evidence, and electrochemical controls that assess transport and thermal effects. Strategies including doping, vacancies, heterojunctions, axial coordination, defect engineering, and applied magnetic fields are summarized, followed by perspectives on physics-informed machine learning, artificial intelligence, and operando sensing for catalyst screening and dynamic regulation.

Facing the dual challenges of energy shortage and environmental degradation, photocatalysis and electrocatalysis have emerged as key technologies for converting small molecules into value-added chemicals, yet their conflicting requirements on the electronic structure of catalysts prevent a single material from freely switching between the two modes. Here, we demonstrate a feasible strategy for achieving on-demand switching between these catalytic functions in a single ferroelectric heterojunction, Pd-C₃N₄@In₂Se₃, through polarization engineering. Using first-principles density functional theory calculations, we show that reversing the polarization direction of the α-In2Se3 layer induces a nonvolatile electronic phase transition. The downward polarization (P↓) configuration exhibits metallic behavior, whereas the upward polarization (P↑) state becomes semiconducting with a type-II band alignment. This transition arises from polarization-dependent interfacial built-in electric fields and charge transfer differences. Notably, the metallicity of the P↓ configuration is localized predominantly within the In₂Se₃ layer rather than delocalized over the entire heterostructure. This arises because the enhanced interfacial charge transfer, driven by the larger work-function difference, selectively populates the conduction band of In₂Se₃, pushing its band edge across the Fermi level, while the Pd-C₃N₄ layer remains semiconducting due to charge depletion and the absence of gap-closing hybridization at the interface. In the P↑ state, the heterojunction acts as an efficient photocatalyst for overall water splitting, with band edges straddling the redox potentials. Under illumination, photogenerated electrons and holes make the hydrogen evolution reaction and oxygen evolution reaction thermodynamically spontaneous. In contrast, the metallic P↓ state serves as an excellent electrocatalyst for hydrogen evolution, delivering a limiting potential as low as −0.11 V, attributed to strengthened N 2p and H 1s orbital hybridization. These findings resolve the conflicting electronic requirements of photocatalysis and electrocatalysis and offer a new paradigm for designing smart, dual-functional catalysts adaptable to varying energy inputs, providing valuable theoretical guidance for future experimental realization of switchable catalytic systems.