Unravelling of the chemistry and the performance in the oxygen reduction reaction of carbon nitride-supported bimetallic electrocatalysts through X-ray photoelectron spectroscopy

TL;DR

This study investigates the surface chemistry and electrochemical performance of bimetallic carbon nitride-supported catalysts in oxygen reduction, revealing insights into their reaction mechanisms through advanced spectroscopic and electrochemical analyses.

Contribution

It provides a detailed correlation between surface chemical states and ORR activity in bimetallic CN-supported electrocatalysts, advancing understanding of their reaction pathways.

Findings

XPS reveals surface elemental concentrations and chemical environments.

Electrochemical tests show improved ORR activity with specific bimetallic compositions.

Surface interactions influence the reaction mechanism and kinetics.

Abstract

Five bimetallic electrocatalysts (ECs) including a carbon nitride (CN) support are synthesised through the pyrolysis of a solid precursor obtained through sol-gel and gel-plastic processes. The resulting ECs are characterised through ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectroscopy) and XPS (X-ray Photoelectron spectroscopy); their performance and reaction mechanism in the oxygen reduction reaction (ORR) are evaluated with the CV-TF-RRDE method (Cyclic Voltammetry Thin-Film Rotating Ring-Disk Electrode). Special attention is given to XPS results with the aim to carry out a thorough investigation of the surface concentration and the chemical environments of the different elements, as well as providing information on the structure of the metal components of the ECs and their interactions with the carbon nitride support. The correlation of the results obtained from the chemical analyses, XPS and the electrochemical studies allows to improve the fundamental understanding of the factors controlling the ORR kinetics and reaction pathway in bimetallic CN-supported ECs.