Efficient urea-assisted water electrolysis at 1500 mA cm−2 for 1100 h over in-situ produced active NiOOH species

Lignin-derived carbon-encapsulated heterojunction promotes in-situ NiOOH formation. • Self-Supported nanoarchitecture enables mass transfer and mechanical robustness. • Lignin-derived carbon-encapsulated improves corrosion resistance. • LC@FeNi 3 /Ni 2 V 2 O 7 stable operates for 1100 h at 1500 mA cm −2 . Although Ni-based catalysts hold promise for replacing the oxygen evolution reaction with the urea oxidation reaction (UOR) in water electrolysis to energy-saving hydrogen production, their activity and long-term stability require further improvement. Herein, we developed a self-supported catalyst composed of lignin-derived carbon (LC) encapsulating a FeNi 3 /Ni 2 V 2 O 7 heterojunction (LC@FeNi 3 /Ni 2 V 2 O 7 ) to tackle these challenges. LC@FeNi 3 /Ni 2 V 2 O 7 requires low potentials of 1.22 V and 1.39 V at 10 and 1000 mA cm −2 . According to operando analysis, the UOR follows an indirect mechanism on the LC@FeNi 3 /Ni 2 V 2 O 7 surface. This reaction pathway is facilitated by the synergy between the lignin-derived carbon and the heterointerfaces, which promotes the generation of active NiOOH species and enables a lower potential than catalysts without these components. In addition, the self-supporting structure ensures efficient gas-liquid release, while the carbon layer enhances corrosion resistance, allowing it to achieve a current density of 1.5 A cm −2 at only 1.84 V under non- membrane electrode assembly conditions, with a potential decay of only 100 mV over 1100 h, demonstrating its potential for commercial applications. This work presents not only an efficient UOR catalyst but also a novel strategy for engineering lignin-derived carbon materials to achieve industrial-scale urea-assisted water electrolysis. Download: Download high-res image (192KB) Download: Download full-size image