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CO 2 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 CO 2 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.

This manuscript reports the electrosynthesis of ammonia from nitrate catalysed Cu derived from Cu2O materials. Cu2O (111) and (100) preferential grain orientations were prepared through electrodeposition. Cu derived from Cu2O (111) is more active and selective for ammonia formation than Cu2O (100) derived Cu. The highest faradaic efficiency (FE) was achieved for both catalysts at −0.3 V vs RHE, with Cu derived from Cu2O (111) reaching up to 80 %. Additional measurements with quasi‐in situ X‐ray photoelectron spectroscopy and in situ Raman spectroscopy revealed that Cu0 is the active phase during the reaction. The stability of the catalysts was examined by ex situ methods such as SEM, XRD and ICP elemental analysis. The catalysts underwent severe morphological changes as a function of the applied potential and the reaction time, most likely due to the dissolution and redeposition of Cu. After 3 hours of reaction, the entire surface of the catalysts was reconstructed into nanoneedles. The FE after 3 hours remained higher for the Cu derived from Cu2O (111), suggesting that the activity is dependent on the initial structure and the different rates of dissolution and re‐deposition.

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Co(HBMIM Ph2 ) 2 ](BF 4 ) 2 (1) [HBMIM Ph2 = bis(1-methyl-4,5-diphenyl-1H-imidazol-2-yl)methane] was investigated for its electrocatalytic hydrogen evolution performance in DMF using voltammetry and during controlled potential/current electrolysis (CPE/ CCE) in a novel in-line product detection setup. Performances were benchmarked against three reported molecular cobalt hydrogen evolution reaction (HER) electrocatalysts, [Co-(2) (dmgBF 2 = difluoroboryldimethylglyoximato), [Co(TPP)] (3) (TPP = 5,10,15,20-tetraphenylporphyrinato), and [Co(bapbpy)Cl](Cl) (4) [bapbpy = 6,6'-bis-(2aminopyridyl)-2,2'-bipyridine], showing distinct performances differences with 1 being the runner up in H 2 evolution during CPE and the best catalyst in terms of overpotential and Faradaic efficiency during CCE. After bulk electrolysis, for all of the complexes, a deposit on the glassy carbon electrode was observed, and post-electrolysis X-ray photoelectron spectroscopy (XPS) analysis of the deposit formed from 1 demonstrated only a minor cobalt contribution (0.23 %), mainly consisting of Co 2 + . Rinse tests on the deposits derived from 1 and 2 showed that the initially observed distinct activity was (partly) preserved for the deposits. These observations indicate that the molecular design of the complexes dictates the features of the formed deposit and therewith the observed activity.