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There is an urgent need for cost-effective strategies to produce hydrogen from renewable net-zero carbon sources using renewable energies. In this context, the electrochemical hydrogen evolution reaction can be boosted by replacing the oxygen evolution reaction with the oxidation of small organic molecules, such as ethylene glycol (EG). EG is a particularly interesting organic liquid with two hydroxyl groups that can be transformed into a variety of C1 and C2 chemicals, depending on the catalyst and reaction conditions. Here, a catalyst is demonstrated for the selective EG oxidation reaction (EGOR) to formate on nickel selenide. The catalyst nanoparticle (NP) morphology and crystallographic phase are tuned to maximize its performance. The optimized NiS electrocatalyst requires just 1.395 V to drive a current density of 50 mA cm-2 in 1 m potassium hydroxide (KOH) and 1 m EG. A combination of in situ electrochemical infrared absorption spectroscopy (IRAS) to monitor the electrocatalytic process and ex situ analysis of the electrolyte composition shows the main EGOR product is formate, with a Faradaic efficiency above 80%. Additionally, C2 chemicals such as glycolate and oxalate are detected and quantified as minor products. Density functional theory (DFT) calculations of the reaction process show the glycol-to-oxalate pathway to be favored via the glycolate formation, where the CC bond is broken and further electro-oxidized to formate.

A comprehensive study was conducted on the synthesis of Cu-MnOx catalysts using a one-pot hydrothermal method followed by a calcination step. These catalysts were thoroughly characterized using techniques such as X-ray diffraction (XRD), X-ray fluorescence (XRF), N2 physisorption, X-ray photoelectron spectroscopy (XPS), temperature programmed desorption and reduction (TPD and TPR), and advanced transmission electron microscopy (TEM). The results revealed that the Cu:Mn molar ratio of the precursors, Cu(NO3)2 and KMnO4, had a significant impact on the crystalline structure and morphology of the synthesized samples. A Cu-doped cryptomelane with a nanorod morphology was observed when the Cu:Mn molar ratio was 0.05. Conversely, a mixture of Cu-doped cryptomelane nanorods, Mn2O3, and Cu1.5Mn1.5O4 spinel nanoparticles was formed at molar ratios of 0.1 and 0.25. The catalytic activities of these catalysts for CO oxidation followed the order: 0.25Cu-MnOx ≈ 0.1Cu-MnOx > 0.05Cu-MnOx > cryptomelane. A good correlation was found between the catalytic performance and reducibility of the catalysts under CO atmosphere that can be related to the ability of the samples to activate the CO molecule. The high reducibility of the sample even at room temperature suggest that the CO oxidation over the synthesized Cu-MnOx catalysts may follow a Mars van Krevelen model.

The energy efficiency of water electrolysis is limited by the sluggish reaction kinetics of the anodic oxygen evolution reaction (OER). To overcome this limitation, OER can be replaced by a less demanding oxidation reaction, which in the ideal scenario could be even used to generate additional valuable chemicals. Herein, we focus on the electrochemical reforming of ethanol in alkaline media to generate hydrogen at a Pt cathode and acetate as a co-product at a NiCoSe anode. We first detail the solution synthesis of a series of NiCoSe electrocatalysts. By adjusting the Ni/Co ratio, the electrocatalytic activity and selectivity for the production of acetate from ethanol are optimized. Best performances are obtained at low substitutions of Ni by Co in the cubic NiSe phase. Density function theory reveals that the Co substitution can effectively enhance the ethanol adsorption and decrease the energy barrier for its first step dehydrogenation during its conversion to acetate. However, we experimentally observe that too large amounts of Co decrease the ethanol-to-acetate Faradaic efficiency from values above 90% to just 50 %. At the optimized composition, the NiCoSe electrode delivers a stable chronoamperometry current density of up to 45 mA cm, corresponding to 1.2 A g, in a 1 M KOH + 1 M ethanol solution, with a high ethanol-to-acetate Faradaic efficiency of 82.2% at a relatively low potential, 1.50 V vs. RHE, and with an acetate production rate of 0.34 mmol cm h.