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CO2 electroreduction to formate powered by renewable energy is an attractive strategy to recycle carbon. Electrode materials showing high selectivity for formate at high current densities are post-transition metals such as Sn, In, Pb, Hg, and Bi. Scaling up the CO2 electroreduction technology to industrial size will require, among other things, maximization of selectivity at high current densities. We show here that InBi electrocatalysts provide enhanced selectivity compared to pure In and Bi and that a proper formulation of the catalyst layer can have a profound impact on the performance of gas diffusion electrode electrolyzers. The best performing electrodes screened in this study show nearly 100% current efficiency at current densities up to 400 mA cm-2 for 2 h. Additionally, one electrode was shown to operate at a current density of 200 mA cm-2 for 48 h at a current efficiency of 85% and remained operating with a current efficiency above 50% for 124 h.

CO2 electroreduction powered by renewable energy is an attractive strategy to close the carbon cycle. Among the possible reduction products, CO is of particular interest due to its large industrial applications. Transition metals in the Pt group are able to electrochemically reduce CO2 to CO, but suffer from CO surface poisoning, which causes a quick deactivation and overall sluggish kinetics. Here, we show that by introducing In to Pd-rich bimetallic particles we can tune the selectivity and limit the surface poisoning of these catalysts. The addition of large amounts of In blocks CO2 reduction activity and leads to a material selective for hydrogen evolution and insensitive to CO poisoning. This study provides insights into the dependence of CO2 reduction selectivity on the composition of Pd-In nanoparticles, revealing the effect that different phases have on catalytic activity. The application of similar screenings to other bimetallic systems can potentially yield cheap, selective, and poison-resistant catalysts for electrochemical applications.

CO2 electroreduction to formate powered by renewable energy is an attractive strategy to recycle air-based carbon. At the moment, the electrode materials showing high selectivity for formate at high current density are post transition metals such as In, Sn, Bi, and Pb. Scaling up the CO2 electroreduction technology to industrial size requires, among other things, cheap and clean methods to produce cathode materials in the form of particles to fabricate the square meters of the electrode surface area needed for the industrial electrolyzers. We show here that it is possible to easily produce catalytic powders based on Sn and Pb via a process known as cathodic disintegration, driving the reaction with electric power and avoiding the use of organic solvents, stabilizers, and reducing agents. The catalysts produced with this method are highly selective for the reduction of CO2 to formate and show promise for use in industrial electrolyzers. Moreover, the process of cathodic disintegration is quick and clean, it has a high atom efficiency, it uses dilute aqueous electrolytes as solvents, and it has the possibility to be driven by renewable energy.

Large scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different variables are known to affect the performance of GDEs. Especially regarding the catalyst loading, there are diverging trends reported in terms of activity and selectivity, e.g. for CO2 reduction to CO. We have used shear–force based Au nanoelectrode positioning and scanning electrochemical microscopy (SECM) in the surface-generation tip collection mode to evaluate the activity of Au GDEs for CO2 reduction as a function of catalyst loading and CO2 back pressure. Using a Au nanoelectrode, we have locally measured the amount of CO produced along a catalyst loading gradient under operando conditions. We observed that an optimum local loading of catalyst is necessary to achieve high activities. However, this optimum is directly dependent on the CO2 back pressure. Our work does not only present a tool to evaluate the activity of GDEs locally, it also allows drawing a more precise picture regarding the effect of catalyst loading and CO2 back pressure on their performance., Large scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies.

openaire: EC/H2020/722614/EU//ELCOREL CO2 electroreduction powered by renewable energy is an attractive strategy to recycle air-based carbon. One of the current challenges for the scale up of the technology is that the catalysts that show high faradaic yield at high current density (post-transitional metals such as In, Sn, Bi, Pb) suffer from very high overpotentials of more than 1 V. On the other hand, Pd can convert CO2 to formate with almost no overpotential, but is readily poisoned by CO and deactivates when trying to reach industrially relevant currents. In this work we show the effect of the interaction of In and Pd in bimetallic nanoparticles, reaching the conclusion that this interaction causes a loss of selectivity towards formate and at the same time suppresses CO poisoning of Pd sites. The results of the catalyst characterization suggest the formation of intermetallic PdIn compounds that in turn cause the aforementioned behavior. Based on these results, it seems that geometric and electronic effects in Pd based intermetallic compounds can alleviate CO poisoning on Pd sites. In the case of PdIn intermetallics this leads to the loss of CO2 reduction activity, but this strategy may be useful for other electrochemical reactions that suffer from the same problem of deactivation. It remains to be seen if intermetallic compounds of Pd with other elements can yield viable CO2 reduction catalysts.