To improve the electrocatalytic conversion of carbon dioxide (CO₂) into C₂₊ products (such as ethylene (C₂H₄) and ethanol (CH₃CH₂OH), etc.) is of great importance, but remains challenging. Herein, we proposed a strategy that directs the C–C coupling pathway through enriching and confining the carbon monoxide (CO) intermediate to internal pores of Cu nanocubes, for electrocatalytic reduction of CO₂ into C₂₊ chemicals. In H-type cell, the Faraday efficiency (FE) for ethylene and ethanol reaches 70.3% at −1.28 V versus the reversible hydrogen electrode (vs. RHE), with a current density of 47.9 mA·cm⁻². In flow cell, the total current density is up to 340.3 mA·cm⁻² at −2.38 V (vs. RHE) and the FE for C₂₊ products is 67.4%. Experimental and theoretical studies reveal that both the CO intermediate adsorption and C–C coupling reaction on such an internal porous catalyst are facilitated, thus improving CO₂-to-C₂₊ conversion efficiency.

To develop high-performance metal-organic frameworks (MOFs) for catalysis is of great importance. Here, we synthesized the mesoporous Cu_3−xZn_x(BTC)₂ (BTC = benzene-1,3,5-tricarboxylate) nanocubes in a deep eutectic solvent of ZnCl₂/ethylene glycol solution. The route can proceed at room temperature and the reaction time needed is shortened to be 30 min, which is superior to the conventional solvothermal route that usually needs high temperature and long reaction time. The formation mechanism of the mesoporous Cu_3−xZn_x(BTC)₂ nanocubes in deep eutectic solvent (DES) was investigated by in situ synchrotron X-ray diffraction/small angle X-ray scattering/X-ray absorption fine structure conjunction technique. The mesoporous Cu_3−xZn_x(BTC)₂ nanocubes exhibit high catalytic activity and reusability for cyanosilylation reaction of benzaldehyde and aerobic oxidation reaction of benzylic alcohol.

To produce metal-organic framework (MOF) catalysts with both high activity and durability is interesting but challenging. We report an amorphous MOF (NH₂-MIL-68), which combines the advantages of (1) a large number of open metal sites, (2) the basic building blocks and connectivity of crystalline NH₂-MIL-68, and (3) hierarchically meso- and microporous structure. It exhibits high performances in electrocatalytic reduction of CO₂ and photochemical cycloaddition of CO₂ under mild conditions. For the former reaction, the maximum Faradaic efficiency for product formic acid (FE_HCOOH) reaches 93.3% with a current density of 34.2 mA·cm⁻² at −2.05 V vs. Ag/Ag⁺ catalyzed by amorphous NH₂-MIL-68, while the crystalline NH₂-MIL-68 shows FE_HCOOH of 67.7% with considerable productions of CO and H₂ at the same experimental conditions. For the photochemical cycloaddition of CO₂ with styrene oxide, the yield by amorphous NH₂-MIL-68 can reach 94.1% at 12 h, which is higher than the reported value under similar conditions. The structure–efficiency relationship of the catalyst for the two reactions was investigated. This work opens up new possibility for designing high-performance MOF and MOF-based catalysts.

To construct the heterojunctions of TiO₂ with other compounds is of great importance for overcoming its inherent shortages and improving the visible-light photocatalytic performance. Here we propose the construction of TiO₂/covalent organic framework (COF) heterojunction with tight connection by a supercritical CO₂ (SC CO₂) method, which helps bridging the transformation paths for photo-induced charge between TiO₂ and COF. The produced TiO₂/COF heterojunction performs a H₂ evolution of 3,962 μmol·g^-1·h^-1 under visible-light irradiation, which is ~ 25 times higher than that of pure TiO₂ and 4.5 folds higher than that of TiO₂/COF synthesized by the conventional solvothermal method. This study opens up new possibilities for constructing heterojunctions for solar energy utilization.

The electroreduction of CO₂ to valuable chemicals and fuels offers an effective mean for energy storage. Although CO₂ has been efficiently converted into C₁ products (e.g., carbon monoxide, formic acid, methane and methanol), its convention into high value-added multicarbon hydrocarbons with high selectivity and activity still remains challenging. Here we demonstrate the formation of multi-shelled CuO microboxes for the efficient and selective electrocatalytic CO₂ reduction to C₂H₄. Such a structure favors the accessibility of catalytically active sites, improves adsorption of reaction intermediate (CO), inhibits the diffusion of produced OH^- and promotes C-C coupling reaction. Owing to these unique advantages, the multi-shelled CuO microboxes can effectively convert CO₂ into C₂H₄ with a maximum faradaic efficiency of 51.3% in 0.1 M K₂SO₄. This work provides an effective way to improve CO₂ reduction efficiency via constructing micro- and nanostructures of electrocatalysts.

It is of great importance to develop facile strategies to synthesize catalysts with desirable compositions and structures for high-performance photocatalytic hydrogen generation. In this work, we put forward an ionic liquid assisted one-pot route for the synthesis of heteroatom-doped Pt/TiO₂ composite material. This route is simple, environmentally benign and adjustable owing to the designable properties of ionic liquids. The as-synthesized Pt/TiO₂ nanocrystals exhibit high activity and stability for the photocatalytic hydrogen generation under simulated solar irradiation. This method can be easily applied to the synthesis of various kinds of metal/TiO₂ composites doped with desirable heteroatoms (e.g., F, Cl, Br, etc).

The application of nickel in electrocatalytic reduction of CO₂ has been largely restricted by side reaction (hydrogen evolution reaction) and catalyst poisoning. Here we report a new strategy to improve the electrocatalytic performance of nickel for CO₂ reduction by employing a nitrogen-carbon layer for nickel nanoparticles. Such a nickel electrocatalyst exhibits high Faradaic efficiency 97.5% at relatively low potential of −0.61 V for the conversion of CO₂ to CO. Density functional theory calculation reveals that it is thermodynamically accomplishable for the reduction product CO to be removed from the catalyst surface, thus avoiding catalyst poisoning. Also, the catalyst renders hydrogen evolution reaction to be suppressed and hence reasonably improves catalytic performance.