Electrocatalytic Reduction of CO2 in Water by a Palladium-Containing Metallopolymer

Mixed Perovskite Phases of BaTiO3/BaTi5O11 for Efficient Electrochemical Reduction of CO2 to CO

One of the most promising approaches in solving the energy crisis and reducing atmospheric CO2 emissions is artificial photosynthetic CO2 reduction. The electrochemical method for CO2 reduction is more appealing since it can be operated under ambient conditions, and the product selectivity strongly depends on the applied potential. Perovskites with ferroelectric properties strongly adsorb linear CO2 molecules. In this study, barium titanate (BaTiO3) perovskite is used as an electrocatalyst to promote CO2 activation and conversion to CO. Perovskite catalysts were prepared by ball-milling followed by annealing at 900 °C for 4 to 6 h in an open atmosphere. The TEM and SEM study shows that the particle size varies in the range of 80-200 nm. Mixed phases of BaTiO3 and BaTi5O11 supported on nitrogen-doped carbon nanotubes are found to be highly active for electrocatalytic CO2 reduction to CO with maximum Faradaic efficiency of 89.4 % at -1.0 V versus Ag/AgCl in CO2 saturated 0.5 KOH solution. This study concludes that mixed phases of BaTiO3 and BaTi5O11 are more active and highly selective for CO2 conversion to CO compared to single-phase BaTiO3.

Copper Nanoclusters Imparted Metalloporphyrin Based Metal-Organic Frameworks for Enhanced CO2 Electroreduction

Strategies that can introduce catalytic auxiliary into electrocatalysts to boost the performance of electrocatalytic CO2 reduction reaction (CO2RR) are meaningful in exploring hybrid electrocatalytic systems. Here, a series of hybrid electrocatalysts (Cu NCs@MOF-545-M, M=Fe, Co and Ni) have been prepared by assembly Cu NCs with MOF-545-M (M=Fe, Co and Ni) and successfully applied in electrocatalytic CO2RR. In the obtained MOF-545-M (M=Fe, Co and Ni), the integration of Cu NCs with MOF-545-M (M=Fe, Co and Ni) can create a hybrid electrocatalytic system that enhances the charge transfer efficiency and electrocatalytic CO2RR activity. Specifically, the optimal Cu NCs@MOF-545-Co presents remarkable FECO over a wide potential range (-0.7 V to -1.0 V), high CO generation rate (8.2 mol m-2 h-1) and excellent maximum energy efficiency (69 %, -0.7 V), which is superior to Cu NCs and MOF-545-Co, and represented to be one of the best performances to date. This work demonstrates a facile approach to significantly improve the FECO by loading metal nanoclusters into MOFs, providing a valuable reference for future studies on hybridization strategies to enhance the performance of electrocatalysts.

Advanced Nanostructured Materials for Electrocatalysis in Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are considered as among the most promising electrochemical energy storage devices due to their high theoretical energy density and low cost. However, the inherently complex electrochemical mechanism in Li-S batteries leads to problems such as slow internal reaction kinetics and a severe shuttle effect, which seriously affect the practical application of batteries. Therefore, accelerating the internal electrochemical reactions of Li-S batteries is the key to realize their large-scale applications. This article reviews significant efforts to address the above problems, mainly the catalysis of electrochemical reactions by specific nanostructured materials. Through the rational design of homogeneous and heterogeneous catalysts (including but not limited to strategies such as single atoms, heterostructures, metal compounds, and small-molecule solvents), the chemical reactivity of Li-S batteries has been effectively improved. Here, the application of nanomaterials in the field of electrocatalysis for Li-S batteries is introduced in detail, and the advancement of nanostructures in Li-S batteries is emphasized.

CO2 Electroreduction on Carbon-Based Electrodes Functionalized with Molecular Organometallic Complexes—A Mini Review

Heterogeneous electrochemical CO2 reduction has potential advantages with respect to the homogeneous counterpart due to the easier recovery of products and catalysts, the relatively small amounts of catalyst necessary for efficient electrolysis, the longer lifetime of the catalysts, and the elimination of solubility problems. Unfortunately, several disadvantages are also present, including the difficulty of designing the optimized and best-performing catalysts by the appropriate choice of the ligands as well as a larger heterogeneity in the nature of the catalytic site that introduces differences in the mechanistic pathway and in electrogenerated products. The advantages of homogeneous and heterogeneous systems can be preserved by anchoring intact organometallic molecules on the electrode surface with the aim of increasing the dispersion of active components at a molecular level and facilitating the electron transfer to the electrocatalyst. Electrode functionalization can be obtained by non-covalent or covalent interactions and by direct electropolymerization on the electrode surface. A critical overview covering the very recent literature on CO2 electroreduction by intact organometallic complexes attached to the electrode is summarized herein, and particular attention is given to their catalytic performances. We hope this mini review can provide new insights into the development of more efficient CO2 electrocatalysts for real-life applications.