Galvanic Exchange as a Novel Method for Carbon Nitride Supported CoAg Catalyst Synthesis for Oxygen Reduction and Carbon Dioxide Conversion

Abstract

A bimetallic alloy of CoAg nanoparticles (NPs) on a carbon nitride (CN) surface was synthesized using a galvanic exchange process for the oxygen reduction reaction (ORR) and carbon dioxide electrocatalytic conversion. The reduction potential of cobalt is ([Co2+(aq) + 2e− → Co(s)], −0.28 eV) is smaller than that of Ag ([Ag+(aq) + e− → Ag(s)], 0.80 eV), which makes Co(0) to be easily replaceable by Ag+ ions. Initially, Co NPs (nanoparticles) were synthesized on a CN surface via adsorbing the Co2+ precursor on the surface of CN and subsequently reducing them with NaBH4 to obtain Co/CN NP. The Co NPs on the surface of CN were then subjected to galvanic exchange, where the sacrificial Co atoms were replaced by Ag atoms. As the process takes place on a solid surface, only the partial replacement of Co by Ag was possible generating CoAg/CN NPs. Synthesized CoAg/CN bimetallic alloy were characterized using different techniques such as powder x-ray diffraction (PXRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and electron diffraction spectroscopy (EDS) to confirm the product. Both the catalysts, Co/CN and CoAg/CN, were evaluated for oxygen reduction reaction in 1M KOH solution and carbon dioxide conversion in 0.5 M KHCO3. In the case of ORR, the CoAg/CN was found to be an efficient electrocatalyst with the onset potential of 0.93 V, which is comparable to commercially available Pt/C having Eonset at 0.91 V. In the electrocatalytic conversion of CO2, the CoAg/CN showed better performance than Co/CN. The cathodic current decreased dramatically below −0.9V versus Ag/AgCl indicating the high conversion of CO2.

Nanosheet Synthesis of Mixed Co3O4/CuOviaCombustion Method for Methanol Oxidation and Carbon Dioxide Reduction

“…The presence of a doublet with BEs of 783 and 797.6 eV reflects the possibility of surface Co(OH) 2 NPs. 26 The Cu 2p core-level spectrum (Figure 2b) shows significant peaks of CuO with BEs of 934 and 953.98 eV, which are attributed to the Cu 2p 3/2 and Cu 2p 1/2 , signals, respectively. 27 There also exist three shake-up satellite signals at 942.49, 944, and 962.68 eV.…”

Recyclable Magnetic Cu/CuFe2O4 Nanocomposites for the Rapid Degradation of 4-NP

“…On one hand, Cu nanocrystals can directly transfer electrons from BH4 − ions to 4-NP. On the other hand, Cu nanocrystals can participate in and boost the electron transfers of neighboring CuFe2O4 nanocrystals between Cu + -Cu 2+ and Fe 2+ -Fe 3+ ion pairs [49][50][51].…”

Colloidal Nanocrystal-Based Electrocatalysts for Combating Environmental Problems and Energy Crisis

“…A clean environment and sustained energy resources are essential for future generations. With growing concerns for both dwindling traditional fossil fuels and global warming, there is an urgent need to develop renewable and environmentally benign alternatives to address these issues of mankind [1][2][3]. Currently, humans are mainly dependent on fossil fuels and thus extract carbon from the geosphere and put it into the atmosphere where it causes global warming.…”