Oxygen-vacancy-rich Ru nanoclusters doped NiCo metal-organic framework for driving overall water electrolysis and supercapacitors

Abstract

Due to the growing demand for clean renewable hydrogen fuel, the rational design of electrode materials' composition and structure holds significant importance in achieving efficient energy storage and conversion in electrochemical energy devices. In this study, we synthesize NiCo-MOF74/NF substrate using a one-step hydrothermal method, after which we successfully deposit a layer of Ru metal nanoclusters on the substrate by electrodeposition. Ru NCs@NiCo-MOF74/NF exhibits an exceptionally large specific surface area and excellent interface effects, demonstrating outstanding performance in both overall water splitting and supercapacitor applications. In a 1 M KOH alkaline solution, the device requires only 1.47 V output voltage to deliver a current density of 10 mA cm−2 for overall water splitting. As a supercapacitor, the unique nanoflower structure of Ru NCs@NiCo-MOF74/NF enables fast and reversible Faradaic reactions, providing high specific capacitance and rate performance. It shows a high areal capacitance of 1.664 mAh cm−2 at 1 mA cm−2, indicating excellent charge storage capacity. Assembled into an asymmetric supercapacitor (ASC) with Ru NCs@NiCo-MOF74/NF as the positive electrode, the device achieves a high energy density of 511.88 μWh cm−2 at a power density of 545.68 μW cm−2. After 5000 cycles, the capacitance retention rate is approximately 100 %, demonstrating remarkable cycling stability. This paves the way for the synthesis of multifunctional catalysts, opening up new possibilities in the field.