Highly Dispersed Indium Oxide Nanoparticles Supported on Carbon Nanorods Enabling Efficient Electrochemical CO₂ Reduction

Abstract

Indium‐based materials can selectively reduce CO2 to formate, but their activities still fall short of expectations to be considered for practical applications. Structural engineering at the nanoscale offers a promising solution. However, it is challenging to directly prepare nanostructures of metallic indium because of its low melting point and high oxophilicity. Herein, a strategy to prepare highly dispersed indium oxide nanoparticles as the precatalyst supported on conductive carbon nanorods from annealing the MIL‐68 (In) precursor is proposed. When assessed in an H‐cell, the product enables CO2 reduction to formate with great faradaic efficiency of around 90% over a wide potential window in 0.5 m KHCO3. When applied in a gas‐diffusion‐electrode‐based flow cell, the catalyst delivers large current density of up to 300 mA cm−2 in 1 m KOH, great formate faradaic efficiency and decent stability. These results indicate the commercial viability of the catalyst even though the carbonate buildup at the gas diffusion electrode remains an issue of future research.

p-Block Indium Single-Atom Catalyst with Low-Coordinated In–N Motif for Enhanced Electrochemical CO2 Reduction

“…39 Taken all together, our results from the H-cell experiments present the first case in which high CO production at low overpotential in eCO 2 RR is achieved using In SAC in aqueous media, and not formate production as many p-block metallic In or In oxide catalysts do. 9,13,40,41 Unsaturated In−N 3 −V sites outperform many In-based alloys or hybrid In-based materials in terms of activity and CO selectivity. 12,42,43 Furthermore, in contrast to the previously reported In SAC for CO generation in ionic liquid/MeCN, 27 we use water as a medium that is less expensive, more eco-friendly, and better suitable for future large-scale applications (Table S4).…”

Triple-Phase Interface Engineering over an In2O3 Electrode to Boost Carbon Dioxide Electroreduction

“…The unprecedented consumption of fossil fuels emits a large amount of CO 2 causing the deterioration of global climate. − Electrocatalytic reduction of CO 2 to fuels and value-added chemicals is regarded as one of the most important strategies to decrease the CO 2 concentration level in the atmosphere. − It is well known that the CO 2 reduction reaction (CO 2 RR) contains multi-step proton-coupled electron transfer processes, involving multiple intermediates and pathways, consequently resulting in sluggish reaction kinetics and complicated reduction products. − High-performance electrocatalysts are thus needed to realize the CO 2 conversion with a high product yield and selectivity. − In recent years, In 2 O 3 has attracted special attention due to its nontoxicity, abundant reserve, and low cost, , and considerable efforts have been devoted to exploring effective strategies to establish efficient In 2 O 3 -based electrocatalytic systems for CO 2 RR. For example, size or shape regulation, metal doping (V doping), defect engineering (O-vacancies), and heterojunction construction (In 2 O 3 -rGO, multi-walled carbon nanotube/In 2 O 3 , Cu/In 2 O 3 , In 2 O 3 /InN) − have been developed and confirmed to be able to elevate CO 2 RR performances of In 2 O 3 , which are mainly originated from the increase in electrochemically active surface areas, improvement of electrical conductivity, and optimization of intrinsic activity. Besides the properties of catalysts themselves, the triple-phase interface (TPI) (i.e., gas–liquid–solid interface) during an electrocatalytic reaction also plays a critical role in CO 2 RR, which influences the diffusion of reagents to catalytically active sites and subsequent interface catalytic reactions.…”

Gaseous CO2 Electrolysis: Progress, Challenges, and Prospects

“…Liquid products, such as formate and C 2 H 5 OH, can also be obtained through the cathode liquid layer of gaseous CO 2 electrolysis. − Xing et al fabricated the Bi-based electrocatalyst in a GDE and controlled catalyst hydrophobicity by adding PTFE . Compared to bare Bi/C, the Bi/C/30% PTFE GDE exhibited a higher performance, with 76% formate FE obtained at −0.7 V RHE .…”

“…However, significant levels of OH – accelerate the reaction via CO 2 generating byproducts. Pan et al reported the gaseous CO 2 electrolysis performance of fabricated In 2 O 3 @CNR catalyst by a chemical synthesis method and investigated its long-term stability . Because of the higher pH of the bulk electrolyte, the alkaline CO 2 electrolyzer using a 1.0 M KOH catholyte exhibited a higher current density of 275 mA/cm 2 at −0.8 V RHE compared to using 1.0 M KHCO 3 as the electrolyte.…”

“…Pan CNR catalyst by a chemical synthesis method and investigated its long-term stability. 58 Because of the higher pH of the bulk electrolyte, the alkaline CO 2 electrolyzer using a 1.0 M KOH catholyte exhibited a higher current density of 275 mA/cm 2 at −0.8 V RHE compared to using 1.0 M KHCO 3 as the electrolyte. However, a long-term stability test using a 1.0 M KOH catholyte exhibited a slight decrease in current density, and carbonate formation on the GDE surface was observed after the test.…”