Invasive water hyacinth-derived Mo-doped Ni@CNT as a high-performance catalyst for efficient and durable water splitting.

Developing low-cost, efficient, and durable catalysts for hydrogen production is critical for advancing sustainable energy technologies. In this work, we report a bifunctional catalyst derived from water hyacinth (WH), one of the world's most invasive aquatic species, used as a green carbon source. The synthesis involves the growth of Ni-encapsulated carbon nanotubes (CNT) on WH-derived carbon (WHC), followed by Mo doping at 20 wt% based on precursor-calculated metallic Mo content, resulting in a unique architecture designated WHC/Mo-Ni@CNT. It forms a 3D conductive network that integrates CNT with active MoC and Ni sites, improving charge transport and intermediate adsorption. Synergistic electronic interactions between Mo and Ni optimize the surface electronic structure, thus enhancing electrocatalytic performance, as evidenced by low overpotentials of 45 mV and 261 mV for the hydrogen evolution reaction and oxygen evolution reaction, respectively. The overall water splitting is further demonstrated with cell voltages of 1.57 V at 10 mA cm and 1.72 V at 100 mA cm in 1.0 M KOH. It demonstrates a long-term durability (1500 h at 100-200 mA cm) and maintains stable operation at high current densities (up to 1 and 2 A cm). Furthermore, it shows distinct performance in anion exchange membrane water electrolyzer and alkaline seawater. This study presents a scalable and sustainable approach for the development of high-performance catalysts aimed at green hydrogen production, employing invasive WH biomass, thus converting an environmental challenge into a valuable bioresource.