Enhancing Water Splitting Efficiency: Synergistic Electrocatalyst Design with Heterojunctions and Porous Carbon Substrate Architecture

Abstract

The advancement of sustainable energy technologies hinges on the discovery of efficient and durable electrocatalysts capable of facilitating water splitting at elevated current densities. Our work presents a groundbreaking bifunctional catalyst, denoted as NM@NC/CC, which combines the benefits of NiSe2-MoSe2 heterojunctions with nitrogen-enriched porous carbon derived from metal-organic frameworks (MOFs). The integration of these components is designed to harness their combined advantages, which include enhanced electron transfer, improved mass and gas evolution dynamics, and an increased number of catalytically active sites. These features collectively optimize the energetics for both the hydrogen and oxygen evolution half-reactions. As a result, the catalyst facilitates a rapid kinetics for the overall water-splitting process. The NM@NC/CC demonstrates exceptionally low overpotentials, requiring only 91 mV for the HER and 280 mV for the OER to reach a current density of 10 mA cm-2. Even at higher current densities, specifically 100 mA cm-2 for HER and 50 mA cm-2 for OER, the overpotentials are commendably low at 159 mV and 350 mV, respectively. Additionally, a two-electrode setup using this catalyst achieves a 10 mA cm-2 current density with a minimal cell voltage of 1.56 V. The insights gained from this study significantly contribute to the strategic advancement of cutting-edge electrocatalysts tailored for energy conversion technologies.

Keywords: Heterostructure, Porous carbon nanowall, bifunctional electrocatalyst, Overall water splitting