Composition-Tuned PdXvY/G-C3N4 Anodes for Alkaline Glycerol Electrooxidation

Abstract

We report a new family of bimetallic anode catalysts, PdxVy/g-C3N4, synthesized via NaBH4 reduction at varying Pd:V ratios for glycerol electrooxidation (GOR). SEM-EDX, XRD, ICP-MS, and XPS confirm uniform dispersion and Pd-V interaction: g-C3N4 (1 0 0)/(0 0 2) reflections are retained, while a slight 2 theta shift and FWHM broadening of Pd (1 1 1) indicate alloying and reduced crystallite size. Electrochemical testing in 1 M KOH and 0.1 M glycerol + 1 M KOH (CV, LSV, EIS, CA) identifies Pd90V10/g-C3N4 as the top performer, delivering current density up to 7.55 mA cm(-2) in CV and 2.72 mA cm(-2) in LSV with an onset of similar to 0.87 V. The smallest EIS semicircle evidences the lowest charge-transfer resistance; the linear dependence of current on the square of scan rate together with a discernible Warburg element indicates pronounced mass transfer limitations under the tested conditions. Despite this partial mass transfer limitation, optimization of catalyst-layer thickness and loading, electrode porosity, and electrolyte flow is required to fully exploit the current density of Pd90V10/g-C3N4 in practical alkaline glycerol fuel cells. Pd90V10/g-C3N4 shows good operational stability, according to chronoamperometry in 0.1 M glycerol + 1 M KOH; following an initial decay within the first 10 s due to surface poisoning, the current density followed a steady course throughout the remainder of the 3600 s period. Overall, Pd-V synergy coupled with the conductive g-C3N4 support enhances active surface and charge transport, yielding markedly improved GOR activity; Pd90V10/g-C3N4 emerges as a promising anode for direct glycerol fuel cells.