High efficiency and selectivity from synergy: Bi nanoparticles embedded in nitrogen doped porous carbon for electrochemical reduction of CO2 to formate

Recent progress of the electrocatalytic CO2 reduction reaction using porous materials

The electrocatalytic reduction of CO2 is widely recognized as a promising strategy to reduce carbon emissions. However, a huge gap remains between the current state of electrocatalytic CO2 reduction reaction (CO2RR) technology and its practical implementation at an industrial scale. Thus, there is growing interest in developing electrocatalysts that offer high activity, selectivity, and stability. Crystalline porous materials such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and porous carbons have emerged as highly effective catalysts for electrocatalytic CO2RRs. Furthermore, advancements in nanoscale characterization and computational modeling have enabled a deeper understanding of the structure and activity relationships in these materials, highlighting how characteristics of the materials influence the selectivity, catalytic activity, and mass transport efficiency for the electrocatalytic CO2RR. In this review, we summarize the fundamentals of electrocatalytic CO2RRs, highlighting the role of porous materials such as MOFs, COFs, and porous carbon. We also discuss recent trends in the selective formation of different CO2RR products, including CO, HCOOH, CH4, and C2+ products. Key advancements in material design are presented along with challenges and future perspectives.

Bismuth oxycarbonates loaded on nitrogen-doped carbon: an efficient nanocomposite catalyst for electrochemical reduction of CO2 to formate

The consumption of fossil fuels has led to a significant increase in CO2 in the atmosphere, resulting in the greenhouse effect and placing tremendous pressure on the global environment. The electrocatalytic reduction of CO2 to produce the high-value chemical formic acid or formate is an efficient and environmentally friendly method with significant practical implications for achieving carbon neutrality. This study presents a nanocomposite catalyst of bismuth oxycarbonate loaded on nitrogen-doped carbon materials (BOC-NC), prepared using a hydrothermal method. In an H-type electrolytic cell, the BOC-NC-900 °C catalyst exhibited excellent electrochemical CO2 reduction (CO2RR) performance, achieving a faradaic efficiency of 94.9% for formate production and maintaining catalytic stability over 38 h of the CO2RR at -1.0 V vs. RHE, while in a flow-cell configuration, it achieved a current density of 91 mA cm-2, a faradaic efficiency of 90.5% for the formate, and sustained stability over 10 hours at -1.0 V vs. RHE. The synergistic effect generated between BOC and NC enhances the formate selectivity, providing valuable insights for developing composite materials that integrate bismuth-based catalysts with carbon matrices.

Selective CO2 Electroreduction to Formate on Polypyrrole-Modified Oxygen Vacancy-Rich Bi2 O3 Nanosheet Precatalysts by Local Microenvironment Modulation

Challenges remain in the development of highly efficient catalysts for selective electrochemical transformation of carbon dioxide (CO₂ ) to high-valued hydrocarbons. In this study, oxygen vacancy-rich Bi₂ O₃ nanosheets coated with polypyrrole (Bi₂ O₃ @PPy NSs) are designed and synthesized, as precatalysts for selective electrocatalytic CO₂ reduction to formate. Systematic material characterization demonstrated that Bi₂ O₃ @PPy precatalyst can evolve intoBi₂ O₂ CO₃ @PPy nanosheets with rich oxygen vacancies (Bi₂ O₂ CO₃ @PPy NSs) via electrolyte-mediated conversion and function as the real active catalyst for CO₂ reduction reaction electrocatalysis. Coating catalyst with a PPy shell can modulate the interfacial microenvironment of active sites, which work in coordination with rich oxygen vacancies in Bi₂ O₂ CO₃ and efficiently mediate directional selective CO₂ reduction toward formate formation. With the fine-tuning of interfacial microenvironment, the optimized Bi₂ O₃ @PPy-2 NSs derived Bi₂ O₂ CO₃ @PPy-2 NSs exhibit a maximum Faradaic efficiency of 95.8% at -0.8 V (versus. reversible hydrogen electrode) for formate production. This work might shed some light on designing advanced catalysts toward selective electrocatalytic CO₂ reduction through local microenvironment engineering.

Enhanced Electrocatalytic CO2 Reduction of Bismuth Nanosheets with Introducing Surface Bismuth Subcarbonate

The electrocatalytic CO2 reduction reaction (CO2RR) into hydrocarbon products is one of the most promising approaches for CO2 utilization in modern society. However, the application of CO2RR requires optimizing state-of-the-art catalysts as well as elucidating the catalytic interface formation mechanism. In this study, a flower-like nano-structured Bi catalyst is prepared by a facile pulse current electrodeposition method wherein the morphologies could be accurately controlled. Interestingly, nano-structured Bi is inclined to generate Bi2O2CO3 in the air and form a stable Bi2O2CO3@Bi interface, which could enhance the CO2 adsorption and conversion. In-situ Raman spectroscopy analysis also proves the existence of Bi2O2CO3 on the electrode surface. In a practical CO2 reduction test by a flow-cell reactor, the Bi2O2CO3@Bi electrode delivers a high faradaic efficiency of the CO2 to formate/formic acid (~90%) at −1.07 V vs. reversible hydrogen electrode (RHE) with no obvious decay during more than a 10 h continuous test. The introducing surface Bi2O2CO3 in nano-structured Bi supports a promising strategy as well as facile access to prepare improved CO2RR electrocatalysts.

Metal-Organic Frameworks Derived Electrocatalysts for Oxygen and Carbon Dioxide Reduction Reaction

The increasing demands of energy and environmental concerns have motivated researchers to cultivate renewable energy resources for replacing conventional fossil fuels. The modern energy conversion and storage devices required high efficient and stable electrocatalysts to fulfil the market demands. In previous years, we are witness for considerable developments of scientific attention in Metal-organic Frameworks (MOFs) and their derived nanomaterials in electrocatalysis. In current review article, we have discussed the progress of optimistic strategies and approaches for the manufacturing of MOF-derived functional materials and their presentation as electrocatalysts for significant energy related reactions. MOFs functioning as a self-sacrificing template bid different benefits for the preparation of metal nanostructures, metal oxides and carbon-abundant materials promoting through the porous structure, organic functionalities, abundance of metal sites and large surface area. Thorough study for the recent advancement in the MOF-derived materials, metal-coordinated N-doped carbons with single-atom active sites are emerging candidates for future commercial applications. However, there are some tasks that should be addressed, to attain improved, appreciative and controlled structural parameters for catalytic and chemical behavior.

Nanoporous bismuth for the electrocatalytic reduction of CO2 to formate

Bi is an attractive catalyst towards the electrochemical reduction of CO₂ to formate. In this work, nanoporous bismuth was prepared by dealloying Mg₃Bi₂ with tartaric acid (TA) solution, and the size of the primary Bi nanoparticles was adjusted according to the concentration of TA. When the concentration of TA increased from 2 wt% to 20 wt%, the particle size of Bi increased from about 70 nm to 400 nm. The synthesized nanoporous Bi samples were investigated as electrocatalysts for the reduction of CO₂ in KHCO₃ electrolyte, and it was found that the smaller the particle size, the higher the catalytic activity. However, nanoporous Bi comprising 70 nm particles suffered from mass transfer difficulty and sintering during the reaction, whereas the 100 nm nanoporous Bi delivered both a high formate formation current and faradaic efficiency (FE) (16 mA cm^-2, FE > 90% at -0.88 V vs. RHE) and showed excellent durability.

From CO2 to Value-Added Products: A Review about Carbon-Based Materials for Electro-Chemical CO2 Conversion

The global warming and the dangerous climate change arising from the massive emission of CO2 from the burning of fossil fuels have motivated the search for alternative clean and sustainable energy sources. However, the industrial development and population necessities make the decoupling of economic growth from fossil fuels unimaginable and, consequently, the capture and conversion of CO2 to fuels seems to be, nowadays, one of the most promising and attractive solutions in a world with high energy demand. In this respect, the electrochemical CO2 conversion using renewable electricity provides a promising solution. However, faradaic efficiency of common electro-catalysts is low, and therefore, the design of highly selective, energy-efficient, and cost-effective electrocatalysts is critical. Carbon-based materials present some advantages such as relatively low cost and renewability, excellent electrical conductivity, and tunable textural and chemical surface, which show them as competitive materials for the electro-reduction of CO2. In this review, an overview of the recent progress of carbon-based electro-catalysts in the conversion of CO2 to valuable products is presented, focusing on the role of the different carbon properties, which provides a useful understanding for the materials design progress in this field. Development opportunities and challenges in the field are also summarized.

Inside-mode indium oxide/carbon nanotubes for efficient carbon dioxide electroreduction by suppressing hydrogen evolution

The hydrogen evolution reaction is a huge challenge for CO2 electroreduction. Herein, an inside-mode indium oxide/carbon nanotube compound (MWCNTs@In2O3) is developed to maximize the catalytic effect and suppress hydrogen evolution, its HCOOH selectivity can reach up to 92.2% at -16.8 mA cm-2, which is more efficient than In2O3.

Electrocatalysis for CO2 conversion: from fundamentals to value-added products

This timely and comprehensive review mainly summarizes advances in heterogeneous electroreduction of CO₂: from fundamentals to value-added products.

An efficient method to prepare supported bismuth nanoparticles as highly selective electrocatalyst for the conversion of CO2 into formate

We report a cost-effective, straightforward synthesis of a novel electrocatalyst for the reduction of CO2 to formate, which achieves nearly complete Faradaic efficiency (FE) at an overpotential (η) of 0.88 V under ambient conditions. The electrocatalyst was prepared using bismuth subsalicylate as precursor and consists of bismuth nanoparticles (Bi NPs) with an average diameter of 5.5 nm supported on activated carbon.