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The compound material titanium oxycarbide (TiOC) is found to be an effective electrocatalyst for the electrochemical oxidation of ethanol to CO 2 . The complete course of this reaction is one of the main challenges in direct ethanol fuel cells (DEFCs). While TiOC has previously been investigated as catalyst support material only, in this study we show that TiOC alone is able to oxidize ethanol to acetaldehyde without the need of expensive noble metal catalysts like Pt. It is suggested that this behavior is attributed to the presence of both undercoordinated sites, which allow ethanol to adsorb, and oxygenated sites, which facilitate the activation of water. This is a milestone in DEFC research and development and opens up innovative possibilities for the design of catalyst materials for intermediate temperature fuel cells., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Transition metal carbides, especially Mo 2 C, are praised to be efficient electrocatalysts to reduce CO 2 to valuable hydrocarbons. However, on Mo 2 C in an aqueous electrolyte, exclusively the competing hydrogen evolution reaction takes place, and this discrepancy to theory was traced back to the formation of a thin oxide layer at the electrode surface. Here, we study the CO 2 reduction activity at Mo 2 C in a non-aqueous electrolyte to avoid such passivation and to determine products and the CO 2 reduction reaction pathway. We find a tendency of CO 2 to reduce to carbon monoxide. This process is inevitably coupled with the decomposition of acetonitrile to a 3-aminocrotonitrile anion. Furthermore, a unique behavior of the non-aqueous acetonitrile electrolyte is found, where the electrolyte, instead of the electrocatalyst, governs the catalytic selectivity of the CO 2 reduction. This is evidenced by in situ electrochemical infrared spectroscopy on different electrocatalysts as well as by density functional theory calculations., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

The hydrogen evolution reaction (HER) has been crucial for the development of fundamental knowledge on electrocatalysis and electrochemistry, in general. In alkaline media, many key questions concerning pH-dependent structure-activity relations and the underlying activity descriptors remain unclear. While the presence of Ni(OH) 2 deposited on Pt(111) has been shown to highly improve the rate of the HER through the electrode's bifunctionality, no studies exist on how low coverages of Ni(OH) 2 influence the electrocatalytic behavior of Cu surfaces, which is a low-cost alternative to Pt. Here, we demonstrate that Cu(111) modified with 0.1 and 0.2 monolayers (ML) of Ni(OH) 2 exhibits an unusual non-linear activity trend with increasing coverage. By combining in situ structural investigations with studies on the interfacial water orientation using electrochemical scanning tunneling microscopy and laser-induced temperature jump experiments, we find a correlation between a particular threshold of surface roughness and the decrease in the ordering of the water network at the interface. The highly disordered water ad-layer close to the onset of the HER, which is only present for 0.2 ML of Ni(OH) 2 , facilitates the reorganization of the interfacial water molecules to accommodate for charge transfer, thus enhancing the rate of the reaction. These findings strongly suggest a general validity of the interfacial water reorganization as an activity descriptor for the HER in alkaline media., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)