Self-Assembly-Induced Mosslike Fe2O3 and FeP on Electro-oxidized Carbon Paper for Low-Voltage-Driven Hydrogen Production Plus Hydrazine Degradation

Energy-saving electrolytic hydrogen production is the precondition for implementing large-scale hydrogen energy exploitation. Replacing the sluggish water oxidation reaction with thermodynamically more favorable pollutant electro-oxidation (degradation) is a very promising approach to combine energy-efficient hydrogen production and sewage treatment. Herein, a homologous asymmetrical two-electrode configuration, made up of self-assembly induced mosslike Fe 2 O 3 and FeP on electro-oxidized carbon paper (ECP), was used to electrolyze the integrated hydrazine oxidation–hydrogen evolution system. The free-standing Fe 2 O 3 /ECP electrode was fabricated by pyrolyzing iron phthalocyanine/ECP self-assembly in air and serves as an anodic reaction catalyst. Subsequent phosphidation of the Fe 2 O 3 /ECP leads to the formation of the FeP/ECP catalyst for hydrogen evolution reaction. The cross-linked mosslike Fe 2 O 3 and FeP nanoparticles densely covered on the surface of ECP provide richly exposed catalytic sites and the well-distributed stacking holes among nanoparticles offer the expedited electrolyte/gas transmission path. Coupled with hydrazine oxidation, the Fe 2 O 3 /ECP∥FeP/ECP configuration presents a superior cell voltage of only 0.93 V at 10 mA cm –2 for synchronous hydrogen production, which is substantially lower than that of traditional overall water splitting system. Besides the low-voltage-driven energy efficiency, the catalyst electrodes also afford excellent run-to-run reproducibility and stability, as well as good batch-to-batch repeatability. Such a win–win coupling strategy offers the prospect of synchronously achieving energy-saving hydrogen production and the green conversion (or degradation) of hydrazine in wastewater.