Monitoring Active Sites for Hydrogen Evolution Reaction at Model Carbon Surfaces

Carbon is ubiquitous as an electrode material in electrochemical energy conversion devices. If used as support material, the evolution of H2 is undesired on carbon. However, recently carbon-based materials are of high interest as economic and eco-conscious alternative to noble metal catalysts. The targeted design of improved carbon electrode materials requires atomic scale insight into the structure of the sites that catalyse H2 evolution. This work demonstrates that electrochemical scanning tunnelling microscopy under reaction conditions (n-EC-STM) can monitor active sites of highly oriented pyrolytic graphite for the hydrogen evolution reaction. With down to atomic resolution, the most active sites in acidic medium are pinpointed near edge sites and defects, whereas the basal planes remain inactive. Density functional theory calculations support these findings and reveal that only specific defects on graphite are active. Motivated by these results, the extensive usage of n-EC-STM on doped carbon-based materials is encouraged to locate their active sites and guide the synthesis of enhanced electrocatalysts.The authors thank Prof. Plamen Atanassov (University of California, Irvine, USA) and Dr. Jun Maruyama (Osaka Research Institute of Industrial Science and Technology, Japan) for fruitful discussion regarding some experimental results. RMK, RWH and ASB acknowledge the financial support from the German Research Foundation (DFG), in the framework of the projects BA 5795/4-1 and BA 5795/3-1, and under Germany's Excellence Strategy–EXC 2089/1–390776260, cluster of excellence ‘e-conversion’. ASB acknowledges the funding from the European Union's Horizon 2020 research and innovation programme under grant agreement HERMES No. 952184. FCV acknowledges financial support from Spanish MICIUN through RTI2018-095460-B-I00 and María de Maeztu (MDM-2017-0767) grants and a Ramón y Cajal research contract (RYC-2015-18996), and also from Generalitat de Catalunya (grants 2017SGR13 and XRQTC). The use of supercomputing facilities at SURFsara was sponsored by NWO Physical Sciences, with financial support from NWO

Acetaldehyde as an Intermediate in the Electroreduction of Carbon Monoxide to Ethanol on Oxide-Derived Copper

Oxide‐derived copper (OD‐Cu) electrodes exhibit unprecedented CO reduction performance towards liquid fuels, producing ethanol and acetate with >50 % Faradaic efficiency at −0.3 V (vs. RHE). By using static headspace‐gas chromatography for liquid phase analysis, we identify acetaldehyde as a minor product and key intermediate in the electroreduction of CO to ethanol on OD‐Cu electrodes. Acetaldehyde is produced with a Faradaic efficiency of ≈5 % at −0.33 V (vs. RHE). We show that acetaldehyde forms at low steady‐state concentrations, and that free acetaldehyde is difficult to detect in alkaline solutions using NMR spectroscopy, requiring alternative methods for detection and quantification. Our results represent an important step towards understanding the CO reduction mechanism on OD‐Cu electrodes

Press notice. EC agricultural price indices. Trends in EC agricultural price indices (output and input): 1st quarter 1985. 1985.3

The high precious metal loading and high overpotential of the oxygen evolution reaction (OER) prevents the widespread utilization of polymer electrolyte membrane (PEM) water electrolyzers. Herein we explore the OER activity and stability in acidic electrolyte of a combined IrO_<i>x</i>/RuO₂ system consisting of RuO₂ thin films with submonolayer (1, 2, and 4 Å) amounts of IrO_<i>x</i> deposited on top. Operando extended X-ray absorption fine structure (EXAFS) on the Ir L-3 edge revealed a rutile type IrO₂ structure with some Ir sites occupied by Ru, IrO_<i>x</i> being at the surface of the RuO₂ thin film. We monitor corrosion on IrO_<i>x</i>/RuO₂ thin films by combining electrochemical quartz crystal microbalance (EQCM) with inductively coupled mass spectrometry (ICP-MS). We elucidate the importance of submonolayer surface IrO_<i>x</i> in minimizing Ru dissolution. Our work shows that we can tune the surface properties of active OER catalysts, such as RuO₂, aiming to achieve higher electrocatalytic stability in PEM electrolyzers

Synergistic Degradation Mechanism in Single Crystal Ni-Rich NMC//Graphite Cells

Acknowledgments We acknowledge Diamond Light Source for time on beamline I09 under Proposals SI30201-1 and SI30201-2. This work is supported by the Faraday Institution under Grants FIRG044, FIRG024, and FIRG060.Peer reviewedPublisher PD