Electrochemically-grown Chloride-free Cu2O nanocubes favorably electroreduce CO2 to Methane: The interplay of appropriate electrochemical protocol. (20th December 2022)

• Record Type: Journal Article
• Authors: Popović, Stefan; Nazrulla, Mohammed Azeezulla; Šket, Primož; Kamal, Khaja Mohaideen; Likozar, Blaž; Suhadolnik, Luka; Pavko, Luka; Surca, Angelja Kjara; Bele, Marjan; Hodnik, Nejc
• Is Part Of: Electrochimica acta. Volume 436(2022)
• Publication Date: 2022-12-20
• Subjects: Copper nanocubes -- CO2 reduction -- Methane -- Protocol -- Support effect; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.141458
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: Ø Electrodeposition of chloride-free Cu NCs. Ø Activation of Cu NCs by appropriate electrochemical protocol. Ø Support effect towards the selective formation of methane on Cu NCs. Ø Influence of electrochemical double layer cycling and OCP in tuning the activity and selectivity of Cu NCs. Abstract: Nowadays, electrochemical CO2 reduction reaction (CO2 RR) to value-added products represents one of the major challenges in electrocatalysis. Copper-based nanocubes (Cu NCs) have been proposed as the front-runner's catalyst for the production of C2+ products at the industrial level. However, their selectivity (C1 vs. C2 product distribution) is rather complex depending on the dynamic structural transformations, the presence of mixed Cu + /Cu 0 states, the microenvironment, and nanocatalyst-support interactions. Commonly, electrochemically-grown Cu NCs are prepared in the presence of chlorides that acts as a shaping agent. In this study, an optimized electrodeposition method for the synthesis of Cl − -free Cu2 O nanocubes on a glassy carbon substrate with uniform size, shape, and loading is established. The successful preparation of chloride-free cuprous oxide nanocubes (Cu2 O NCs) was confirmed with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) analyses. We report how the electrochemical double-layer capacitance (EDLC) method for electrochemical surface area (ECSA) determination with(out) subsequent return to the open-circuit potential (OCP) conditions before electrolysis influences the CO2 RR activity/selectivity. When Cu2 O NCs are subjected to the EDLC method (often considered a non-invasive method) and exposed to the OCP before electrolysis, they become active for methane (CH4 ) formation. Moreover, the influence of the potential window width (i.e. 200 and 400 mV) in which the EDLC-ECSA is employed and its correlations with the selectivity is presented. We underline the importance of the ECSA determination method and OCP on/off state as a triggering factor for reactivity/selectivity of particular Cu2 O NCs for CO2 RR and further emphasize the reconstructive nature of Cu2 O NCs under CO2 RR relevant conditions. Graphical abstract: Image, graphical abstract