Interfacial Confinement of Alloys on Electrically Conductive g-C3N4 Networks for Enhancing Methanol Electrooxidation

Methanol oxidation reaction (MOR) on monometallic sites is limited because of poor CO tolerance, ineffective reduction behaviour, and low surface regeneration. Engineering alloy sites integrated with strong metal-support interactions provides enhanced interfacial dynamics of the adsorbed intermediates. However, surface enrichment of redox species and their mechanistic pathways depending upon their electronic coupling require further investigation. In this study, uniformly dispersed Pd0.3Cu0.7 alloys were anchored on graphitic carbon nitride (g-C3N4) via solvothermal and pyrolytic approaches, respectively. To regulate the confined distribution in nanocomposites, Pd0.3Cu0.7 alloys were coupled with four distinct wt% of g-C3N4 (10, 20, 30, and 40%). This approach enabled the transformation of g-C3N4 from long-range ordered 2D sheets to short-range domains as evidenced from the disappearance of the PXRD peak (27.6°) and FT-IR analysis (803 cm-1). Further, agglomerated bulk metallic sites (Pd0.3Cu0.7 alloys) and confined particles of Cu and Pd over g-C3N4 support with an average particle size of 4.5 ± 0.2 nm as evidenced from HR-TEM analysis. XPS analysis affirmed the co-existence of Pd0/Pd2+ and Cu0/Cu2+ redox species. The beneficial short-range 2D sheets with adjacent Pd and Cu sites assisted in the removal of CO2 at high anodic potential regions. Considering the performance of catalysts in MOR, Pd0.3Cu0.7/g-C3N4-30% nanocomposite demonstrated a superior mass activity of 692.69 mA mgPd-1 and specific activity of 0.71 mA cm-2. The confined dispersion of electrocatalysts can also be expanded into other energy fields in the future.