Hydrogen Production

Amid the growing depletion of fossil fuels and the pressing need for sustainable energy, renewable energy sources have attracted significant research attention. Hydrogen energy has emerged as a leading alternative due to its high gravimetric energy density (142 MJ kg-1) and potential for zero carbon emissions, making it an ideal clean energy source. Electrochemical water splitting is widely considered one of the most promising methods for large-scale hydrogen production, offering a sustainable solution to meet the rising global energy demand. However, the key challenge lies in developing highly active, cost-effective, and durable electrocatalysts to optimize the efficiency of overall water splitting.

Our research aims to address these challenges by focusing on the design and development of advanced electrocatalysts, specifically chalcogenides, Nickel Cobalt Oxide, layered double hydroxide (LDH), Oxy(hydroxides)-based electrocatalysts, and their hybrid composites. These materials are known for their remarkable electrochemical activity, stability, and scalability. Through precise structural engineering and electronic modulation, we have successfully synthesized efficient bifunctional electrocatalysts, demonstrating significant improvements in both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER).

Fig 1. The schematic diagram of SnS/Nickel Cobalt Oxide/NF preparation (Energy & Fuels 2023, 624–634); (b) electrocatalytic water splitting mechanism (ACS Applied Nano Materials, 2024: 22674–22683)

Recently, we reported the synthesis of ultrathin FeOOH layers grown on Nickel Cobalt Sulfide/Nickel Sulfide nanosheets on nickel foam, demonstrating a highly robust and efficient electrocatalyst for overall water splitting. This material exhibited remarkable stability and performance, positioning it as a promising candidate for large-scale hydrogen production. Additionally, we fabricated a sheet-like Nickel Sulfide/Molybdenum Disulfide / Tungsten disulfide (NMWS) heterostructure on nickel foam using a hydrothermal method, which showcased superior electrocatalytic activity in a 1.0 M KOH electrolyte, with the heterostructure achieving a low cell voltage of 1.73 V at 10 mA cm-2 (International Journal of Hydrogen Energy, 2024: 186-198). The NMWS heterostructure demonstrated excellent charge transfer efficiency and long-term stability, making it ideal for sustainable hydrogen production.

Fig 2. OWS Performance of NM/NCS/NS/NF electrode (Chemosphere (2024): 141016)

In addition, we engineered a Nickel Cobalt Sulfide /Nickel Sulfide nanosheets with ultrathin NiMn-LDH encapsulation over nickel foam (NM/NCS/NS/NF) via a two-step hydrothermal process (Chemosphere (2024): 141016). This NM/NCS/NS/NF electrode demonstrated exceptional bifunctional activity for OER and HER in alkaline and seawater electrolytes, achieving low overpotentials of 282 mV for OER and 171 mV for HER. It exhibited excellent stability during prolonged electrolysis, with cell voltages of 1.54 V and 1.56 V at 10 mA cm-2, outperforming many existing electrocatalysts. This makes it a promising candidate for large-scale, cost-effective water electrolysis, especially for seawater electrolysis, enabling sustainable hydrogen generation from renewable resources.

Supercapacitor

The growing demand for efficient energy storage solutions has driven research into advanced electrochemical energy storage (EES) technologies, particularly hybrid systems that merge the benefits of supercapacitors and batteries. Among these, nanostructured electrode materials have emerged as key enablers of high-performance energy storage due to their enhanced surface area, electrical conductivity, and ion transport capabilities.

Carbon-based materials such as reduced graphene oxide (rGO) provide excellent conductivity and stability, while transition metal oxides like MnO₂, Fe₂O₃, NiO, CuO, and Co₃O₄ facilitate rapid and reversible redox reactions, improving charge storage capacity. However, binary metal oxides often face challenges such as poor conductivity and limited capacitance, necessitating the development of ternary metal oxide composites. These materials, incorporating two distinct metal ions, offer a broader range of oxidation states, improved electrochemical behavior, and enhanced conductivity. In particular, Co₃O₄/CuO/rGO nanocomposites synthesized via hydrothermal methods have demonstrated promising electrochemical properties, making them ideal candidates for supercapatteries. Their unique structural and compositional advantages contribute to higher specific capacity, improved energy and power density, and enhanced cycling stability, positioning them as a viable solution for next-generation energy storage applications.

Analysing the electrode’s behavior at various scan rates revealed a shift between surface and diffusion-controlled processes. As the scan rate increased from 5 to 100 mV s⁻¹, the capacitive contribution rose from 35% to 63%, indicating dominant capacitive control. The Co₃O₄/CuO/rGO composite was hybridized with rGO to enhance electrochemical properties and conductivity, demonstrating high specific capacity as a supercapattery electrode. A Co₃O₄/CuO/rGO//Activated carbon supercapattery exhibited 808 W kg⁻¹ power density, 75 Wh kg⁻¹ energy density, and 337 C g⁻¹ specific capacity at 1 A g⁻¹. It also maintained 99% retention after 10,000 cycles, highlighting its potential for energy storage applications (International Journal of Hydrogen Energy 97 (2025): 1212-1226).

In other case, Strategic engineering of NiO/Co₃O₄/rGO hybrid composite enhances supercapattery performance. The hydrothermal assembly of NiO/Co₃O₄@rGO arrays enable superior electrochemical behavior, with rGO serving as a conductive scaffold for efficient electron transport. In a three-electrode setup, the electrode delivers 711 C g⁻¹ at 1 A g⁻¹. The synergistic effect in the NiO/Co₃O₄@rGO//α-Fe₂O₃/rGO asymmetric supercapattery achieves 76.2 Wh kg⁻¹ energy density and 795.3 W kg⁻¹ power density, retaining 99% Coulombic efficiency over 10,000 cycles. This design offers a promising solution for high-performance, sustainable energy storage (Journal of Energy Storage 86 (2024): 111037).