Carbon-Based Electrode Materials for Electrocatalytic Transformations

Abstract

Industrial processes for the synthesis of chemicals and fuels utilise selective hydrogenation reactions. The need for high temperatures and high pressure of H2 makes these reactions energy intensive and only viable on a large scale, requiring expensive transport of materials. Electrocatalytic hydrogenation (ECH) could potentially bypass these limitations, running at ambient conditions and generating the adsorbed hydrogen in-situ. The interest in new electrocatalyst materials increased in recent years, as ECH offers a synthetic route for fuels and value-added chemicals with a reduced carbon footprint. The development of new low-cost catalyst materials will be paramount for the integration of ECH into economic activities.In this work we focus on heteroatom-modified carbon based electrode materials for the ECH. Carbon materials possess a list of beneficial properties for electrochemical applications: they are widely available, environmentally benign, stable at cathodic potentials and can be tailored towards specific applications. One way of tailoring is to dope the carbon with heteroatoms like nitrogen.Nitrogen-doped carbon thin films have been synthesised using sputter deposition followed by an annealing process, to control graphitisation and nitrogen distribution of the carbon material. These model electrodes were investigated by themselves and as supports for thin nanoparticle films of MoS2 in the ECH and the hydrogen evolution reaction (HER), as the Volmer step of the HER is needed in the ECH. This allowed us to understand the influence of nitrogen moieties on reduction rates in the absence of morphological effects. The results suggest possible strategies for developing electrocatalysts for the ECH based on functional carbons.[1] Orella, M.J.; Román-Leshkov, Y.; Brushett, F.R., Emerging opportunities for electrochemical processing to enable sustainable chemical manufacturing. Current Opinion in Chemical Engineering 2018, 20, 159–167.[2] Behan, J. A.; Stamatin, S. N.; Hoque, M. K.; Ciapetti, G.; Zen, F.; Esteban-Tejeda, L.; Colavita, P. E., Combined Optoelectronic and Electrochemical Study of Nitrogenated Carbon Electrodes. The Journal of Physical Chemistry C 2017, 121 (12), 6596-6604.[3] Nolan, H.; Schröder, C.; Brunet-Cabré, M.; Pota, F.; McEvoy, N.; McKelvey, K.; Perova, T. S.; Colavita, P. E., MoS2/carbon heterostructured catalysts for the hydrogen evolution reaction: N-doping modulation of substrate effects in acid and alkaline electrolytes. Carbon 2023, 202, 70-80.