Ultrafine Rh nanocrystals decorated ultrathin NiO nanosheets for urea electro-oxidation

Abstract

Heterostructured noble metal/transition metal nanohybrids have attracted increasing attention in energy/environment-related electrocatalysis field due to their high activity. In this work, the ultrathin NiO nanosheets (NiO-NSs) decorated with ultrafine Rh nanocrystals (Rh-NCs) electrocatalyst (termed as Rh-NCs/NiO-NSs) is successfully synthesized by using mixed-cyanogels-NaBH4 method and succedent heat treatment. Physical characterizations confirm that as-prepared Rh-NCs/NiO-NSs have 1.6 nm thickness and a large specific surface area of 166.2 m2 g−1, and ultrafine Rh-NCs are uniformly dispersed on surface of NiO-NSs. Electrochemical measurements show that the incorporation of Rh-NCs can promote the generation of NiIIIOOH species and accelerate the oxidation of CO, thus significantly improving the electrocatalytic performance of NiO-NSs for urea electro-oxidation reaction (UEOR). The UEOR current at Rh-NCs/NiO-NSs achieves the 616 mA mg−1 at 1.55 V potential, which is 11.5 times bigger than that at NiO-NSs in 1 M KOH solution with 0.33 M urea. Additionally, Rh-NCs/NiO-NSs also show excellent long-term stability due to improved structural/chemical stability and anti-poisoning capability.