Ni-incorporated N-doped graphitic carbon derived from pomegranate peel biowaste as an efficient OER and HER electrocatalyst for sustainable water splitting

Abstract

The electrochemical energy conversion process must develop effective, long-lasting, and reasonably priced bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this work, we present a simple, sustainable, economical, and scalable method for the preparation of stable and useful nickel nanoparticles on highly porous graphitic carbon doped with nitrogen. Direct pyrolysis followed by carbonization was used to create robust catalysts at different temperatures in an environment containing nitrogen (N₂). The carbon material generated at 600 °C (Ni@NPC-600) shows greater electrochemical efficiency when compared to other catalysts. The synthesized electroactive catalyst Ni@NPC-600 requires a less overpotential 280 mV (114 mV dec⁻¹) for OER and 151 mV (98 mV dec⁻¹) to conduct a HER at 10 mA cm⁻² in 1 M KOH. The active catalyst Ni@NPC-600 shows long-lasting robustness over 90 h with a current loss of <3.33 % and <4.9 % for OER and HER respectively. In addition, the overall water disintegration of Ni@NPC-600/NF//Ni@NPC-600/NF was achieved at 1.51 V with a continuous evolution of H₂ and O₂ at the cathode and anode respectively for approximately 150 h of prolonged robustness with a current reduction of < 4.6 %.