Recent Advances in the Catalyst Design and Mass Transport Control for the Electrochemical Reduction of Carbon Dioxide to Formate

Abstract

Closing the carbon cycle by the electrochemical reduction of CO2 to formic acid and other high-value chemicals is a promising strategy to mitigate rapid climate change. The main barriers to commercializing a CO2 reduction reaction (CO2RR) system for formate production are the chemical inertness, low aqueous solubility, and slow mass transport characteristics of CO2, along with the low selectivity and high overpotential observed in formate production via CO2 reduction. To address those problems, we first explain the possible reaction mechanisms of CO2RRs to formate, and then we present and discuss several strategies to overcome the barriers to commercialization. The electronic structure of the catalyst can be tuned to favor a specific intermediate by adjusting the catalyst composition and tailoring the facets, edges, and corners of the catalyst to better expose the active sites, which has primarily led to increased catalytic activity and selectivity. Controlling the local pH, employing a high-pressure reactor, and using systems with three-phase boundaries can tune the mass transport properties of reactants at the catalyst surface. The reported electrocatalytic performances are summarized afterward to provide insight into which strategies have critical effects on the production of formate.

Towards a broad-operation window for stable CO2electroreduction to HCOOH by a design involving upcycling electroplating sludge-derived Sn@N/P-doped carbon

“…Importantly, the electrochemical reduction of CO 2 to HCOOH is a twoelectron process with high product selectivity, compared to other conversion ways aiming for high-value-added chemicals, and is considered one of the most promising and economically viable reactions. [10][11][12] The core of the CO 2 RR to HCOOH lies in the design of high-efficiency electrocatalysts. Among those electrocatalysts, noble metals, such as Au, 13,14 Ag, 15,16 and even some singleatom catalysts 17,18 are usually preferred for the high selectivity of CO. For the CO 2 RR to HCOOH, Sn, 19,20 Bi, 21,22 Pb, 23,24 In, 25,26 Pd (ref.…”

Zn- and Ti-Doped SnO2 for Enhanced Electroreduction of Carbon Dioxide

“…This is one of the numerous routes proposed in literature for the optimization of the mass transport, including optimization of the morphology of the catalyst or electrodes, composition of the electrodes and control over local pH. In practice, this can be achieved by an increase of the CO 2 solubility and employment of high-pressure reactors or three-phase-boundary electrodes and reactors, in which gaseous CO 2 is directly transported to the catalyst surface through GDL [ 61 ]. It was shown by Deng et al that this change can result in an improvement in a Bi 2 O 3 @C−800 catalyst performance from FEHCOOH of 92% with a partial current density of 7.5 mA cm −2 at −0.9 V vs. RHE in the H-type cell, to FEHCOOH of 93% with a high current density of over 150 mA cm −2 at the same potential in the flow cell configuration [ 49 ].…”

Towards the Large-Scale Electrochemical Reduction of Carbon Dioxide

“…Mostly, enhancing the catalyst activity in electrochemical CO2 reduction involves tailoring the crystal morphology to better expose the active catalytic sites [66,67]. This strategy is known to provide energetically preferred sites for the adsorption of the desired CO2 reduction intermediate.…”