CuO-Ni(OH)2 nanosheets as effective electro-catalysts for urea oxidation

Abstract The electrooxidation of urea is identified as a prospective route for the degradation of urea-rich wastewater and hydrogen generation. Here, we report a controllable synthetic strategy to develop CuO-Ni(OH)2-d nanosheets by deliberately selecting S2O32− as the coordinating etchant toward to Cu2O template and optimize the reaction conditions. The CuO-Ni(OH)2-d is composed of CuO quadrangle nanosheets (100–200 nm) dispersed with Ni(OH)2 nanoparticles. As predicted, The CuO-Ni(OH)2-d nanosheets catalysts exhibit high UOR activities at 1.41 V vs. RHE to achieve the current density of 10 mA cm−2 under the condition of 1 M KOH with 0.33 M urea. The CuO-Ni(OH)2-d nanosheets catalyst also emerges a higher current density of 21.5 mA cm−2, which is about 5.3, 6.8, 30, and 2 times larger than those of commercial Ni(OH)2, CuO-Ni(OH)2-a, CuO-Ni(OH)2-b and CuO-Ni(OH)2-c at 1.52 V vs. RHE, respectively. In particular, the CuO-Ni(OH)2-d nanosheets catalysts exhibited the best catalytic stability performance. After the 36 h I-T test, the current density has no noticeable decreasing compared with the initial current density. This work could present a strategy for the design of advanced electrode materials that can be further applied in urea-rich wastewater remediation.