Cu₂O-Derived PtCu Nanoalloy toward Energy-Efficient Hydrogen Production via Hydrazine Electrolysis under Large Current Density

Electrocatalytic overall water splitting (OWS), powered by a renewable energy source, is a promising strategy for hydrogen production. However, the OWS system usually requires large energy consumption due to the sluggish kinetics of the anodic oxygen evolution reaction. Herein, we fabricated a PtCu nanoalloy (PtCu-NA) through a template-assisted method and evaluated its bifunctional activities for both hydrogen evolution reaction (HER) in 1 M KOH and hydrazine oxidation reaction (HzOR) in 1 M KOH + 1 M hydrazine. Remarkably, the interplanar crystal spacing of PtCu-NA was larger than that of standard PtCu and closer to that of Pt, which can be attributed to the template-assisted synthesis method. Thus, the as-prepared PtCu-NA needs low overpotentials of 224 and 668 mV to drive HER and HzOR at 100 and 200 mA cm-2, respectively, which are much better than those of commercial Pt/C (453 and 1081 mV). After coupling the HER and HzOR together, the overall hydrazine splitting (OHzS) cell needs a small voltage of 0.666 V to deliver 200 mA cm-2 in 1 M KOH + 1 M hydrazine, outperforming the Pt/C (0.792 V). Impressively, the assembly OHzS cell could run stably for more than 110 h. These performances can be attributed to the regulation of the crystal structure of the PtCu alloy and the synergistic effect between Pt and Cu.