Ni-Based Composites from Chitosan Biopolymer a One-Step Synthesis for Oxygen Evolution Reaction

Behzad Aghabarari,Maria Jesús Lázaro Elorri,Maria Victoria Martínez-Huerta,Maricarmen Capel-Sánchez,José Manuel Luque-Centeno

doi:10.3390/catal9050471

Abstract

Cost-efficient and sustainable electrocatalysts for oxygen evolution reaction (OER) is highly desired in the search for clean and renewable energy sources. In this study, we develop a new one-step synthesis strategy of novel composites based on Ni and molybdenum carbide embedded in N- and P-dual doped carbon matrices using mainly chitosan biopolymer as the carbon and nitrogen source, and molybdophosphoric acid (HMoP) as the P and Mo precursor. Two composites have been investigated through annealing a mixture of Ni/chitosan and HMoP with two unlike carbon matrices, melamine and graphene oxide, at a high temperature. Both composites exhibit similar multi-active sites with high electrocatalytic activity for OER in an alkaline medium, which is comparable to the IrO2 catalyst. For this study, an accurate measurement of the onset potential for O2 evolution has been used by means of a rotating ring-disk electrode (RRDE). The use of this method allows confirming a better stability in the chitosan/graphene composite. This work serves as a promising approach for the conversion of feedstock and renewable chitosan into desired OER catalysts.

Highlights

Electrochemical water splitting from renewable energy is of particular interest because it is considered a clean and sustainable process [1,2]
The efficiency of electrochemical water splitting is dependent on two half reactions, in other words, the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode [3,4]
We developed a new one-step synthesis strategy of multi-active site composites based on Ni and molybdenum carbide embedded in N- and P-dual doped carbon matrices

Summary

Introduction

Electrochemical water splitting from renewable energy (wind- or solar-derived electricity) is of particular interest because it is considered a clean and sustainable process [1,2]. Coupling transition metal species with N-doped carbon-based materials is one of the most popular strategies for tailoring active and durable advanced composite electrocatalysts. These compounds combine unique properties, such as high electrical conductivity and enhanced electron transfer, ascribed to the N incorporation into the carbon matrix with a modulated distribution of charge density [8,23]. The nature of the active sites of the electrocatalysts was discussed based on various physical and chemical characterizations Both composites exhibited enhanced electrocatalytic activity for the OER in an alkaline medium, being similar to the IrO2 catalyst. The unique nature of graphene material improved the electrochemical properties of the multi-active site composite, Ni/Mox C/rGOCS, showing higher electrochemical durability

Results and Discussion

Materials and Methods

Conclusions