Porous silver microrods by plasma vulcanization activation for enhanced electrocatalytic carbon dioxide reduction

Design of Mg-Ni binary single-atom catalysts for conversion of carbon dioxide to syngas with a wide tunable ratio: Each species doing its own job or working together to win?

Electrochemical carbon dioxide reduction reaction (eCO2RR) to generate syngas is an appealing strategy for CO2 net reduction. However, it suffers from the inferior faradaic efficiency (FE), selectivity, and difficult modulation of hydrogen/carbon monoxide (H2/CO) ratio. To address these issues, a series of magnesium-nickel (Mg-Ni) dual atomic catalysts with different Ni contents are fabricated on the nitrogen-doped carbon matrix (MgNiX-NC DACs) by one-step pyrolysis. MgNi5-NC electrocatalyst generates 0.51-0.79 H2/CO ratios in a potential range of -0.6 to -1.0 V vs. reversible hydrogen electrode (RHE) and the total FE reaches 100 % with good stability. While a wider range of H2/CO (0.95-4.34) is achieved for MgNi3-NC electrocatalyst in the same overpotential range, which is suitable for typical downstream thermochemical reactions. Introduction of Ni species accelerates the generation of CO, however, there is much less influence on the H2 production as compared with Mg-based single atomic electrocatalyst. According to the experimental results and density functional theory (DFT) calculations, the synergistic effect between Mg and Ni achieves the satisfied results rather than each one fulfill its own duty for selective producing H2 and CO, respectively. This work introduces a feasible approach to develop atomic catalysts on main group metal for more controllable CO2RR.

Advances in Defect Engineering of Metal Oxides for Photocatalytic CO2 Reduction

Photocatalytic CO2 reduction technology, capable of converting low-density solar energy into high-density chemical energy, stands as a promising approach to alleviate the energy crisis and achieve carbon neutrality. Semiconductor metal oxides, characterized by their abundant reserves, good stability, and easily tunable structures, have found extensive applications in the field of photocatalysis. However, the wide bandgap inherent in metal oxides contributes to their poor efficiency in photocatalytic CO2 reduction. Defect engineering presents an effective strategy to address these challenges. This paper reviews the research progress in defect engineering to enhance the photocatalytic CO2 reduction performance of metal oxides, summarizing defect classifications, preparation methods, and characterization techniques. The focus is on defect engineering, represented by vacancies and doping, for improving the performance of metal oxide photocatalysts. This includes advancements in expanding the photoresponse range, enhancing photogenerated charge separation, and promoting CO2 molecule activation. Finally, the paper provides a summary of the current issues and challenges faced by defect engineering, along with a prospective outlook on the future development of photocatalytic CO2 reduction technology.

SnS2/MWNTs/sponge electrode combined with plasma dielectric barrier discharge catalytic system: CO2 reduction and pollutant degradation

SnS2 nanosheets combined with multi-walled carbon nanotubes (MWNTs) were made into sponge electrodes which were used for CO2 reduction reaction (CO2RR) in dielectric barrier discharges (DBD) system. The amounts of formate and formaldehyde produced by CO2 reduction with SnS2/MWNTs/sponge electrode were 299.52 and 31.62 μmol h-1, which were higher than that of MWNTs/sponge electrodes. The addition of pollutants had different degrees of inhibitory effect on CO2 reduction, among which addition of bisphenol A (BPA) had the smallest effect that the degradation rate of BPA was 94.37% and the C1 products remained 204.43 μmol after 60 min discharge. The mechanism of CO2RR was studied by quencher experiment, and the main contribution order of the active substance in DBD system for CO2RR is: H+>e->·OH>·O2-. It was found that the degradation process of pollutants consumed H+ and e- in solution, thereby inhibiting CO2RR. Generally, the SnS2/MWNTs/sponge electrode provided a reference for the design of catalysts for CO2 reduction and pollutant degradation in plasma gas-liquid system.

Recent Advances in Graphitic Carbon Nitride Based Electro-Catalysts for CO2 Reduction Reactions

The electrocatalytic carbon dioxide reduction reaction is an effective means of combating the greenhouse effect caused by massive carbon dioxide emissions. Carbon nitride in the graphitic phase (g-C₃N₄) has excellent chemical stability and unique structural properties that allow it to be widely used in energy and materials fields. However, due to its relatively low electrical conductivity, to date, little effort has been made to summarize the application of g-C₃N₄ in the electrocatalytic reduction of CO₂. This review focuses on the synthesis and functionalization of g-C₃N₄ and the recent advances of its application as a catalyst and a catalyst support in the electrocatalytic reduction of CO₂. The modification of g-C₃N₄-based catalysts for enhanced CO₂ reduction is critically reviewed. In addition, opportunities for future research on g-C₃N₄-based catalysts for electrocatalytic CO₂ reduction are discussed.

Silver-Carbonaceous Microsphere Precursor-Derived Nano-Coral Ag Catalyst for Electrochemical Carbon Dioxide Reduction

The selective and effective conversion of CO2 into available chemicals by electrochemical methods was applied as a promising way to mitigate the environment and energy crisis. Metal silver is regarded as an efficient electrocatalyst that can selectively convert CO2 into CO at room temperature. In this paper, a series of coral-like porous Ag (CD-Ag) catalysts were fabricated by calcining silver-carbonaceous microsphere (Ag/CM) precursors with different Ag content and the formation mechanism of CD-Ag catalysts was proposed involving the Ag precursor reduction and CM oxidation. In the selective electrocatalytic reduction of CO2 to CO, the catalyst 15 CD-Ag showed a stable current density at −6.3 mA/cm2 with a Faraday efficiency (FE) of ca. 90% for CO production over 5 h in −0.95 V vs. RHE. The excellent performance of the 15 CD-Ag catalysts is ascribed to the special surface chemical state and the particular nano-coral porous structure with uniformly distributed Ag particles and pore structure, which can enhance the electrochemical active surface areas (ECSA) and provide more active sites and porosity compared with other CD-Ag catalysts and even Ag foil.

Ultrathin structure of oxygen doped carbon nitride for efficient CO2photocatalytic reduction

Photocatalytic conversion of carbon dioxide into fuels and valuable chemicals is a promising method for carbon neutralization and solving environmental problems. Through a simple thermal-oxidative exfoliation method, the O element was doped while exfoliated bulk g-C₃N₄into ultrathin structure g-C₃N₄. Benefitting from the ultrathin structure of g-C₃N₄, the larger surface area and shorter electrons migration distance effectively improve the CO₂reduction efficiency. In addition, density functional thory computation proves that O element doping introduces new impurity energy levels, which making electrons easier to be excited. The prepared photocatalyst reduction of CO₂to CO (116μmol g^-1h^-1) and CH₄(47μmol g^-1h^-1).

Positively charged silver improve carbon dioxide electroreduction reaction performance by introducing phosphate

For noble metal catalysts such as Au and Ag, the weak adsorption of intermediates is an important factor in limiting the efficiency of CO₂ electroreduction. Positively charged metals, which can lower the energy barriers of intermediate reactions, greatly facilitate the rapid conversion of CO₂ molecules. In this work, a simple in situ synthesis method was utilized to form an Ag₃PO₄ oxide layer on the surface of Ag foil, and the oxidation state of silver retained after pre-reduction. The Ag₃PO₄/Ag catalyst not only increased the electrochemical surface area, but also enhanced the adsorption of intermediates to the active sites, resulting in the catalytic selectivity of 94.4% for the electroreduction of CO₂ to CO. DFT calculations show that through internal electron regulation, PO₄^3- can stabilize the positive state of Ag, thus increasing the Ag-O bond energy, which is conducive to the reduction of the reaction energy barrier and the improvement of catalytic stability.