Boosting hydrogen production via water and urea oxidation using a facile fabricated alkali-etched ZIF-67@Ni(OH)2 electrocatalyst

Abstract

Designing an operative and stable metal electrocatalyst for hydrogen production via water and urea oxidation has been in the spotlight for the past few years. In this work, we have deposited Ni(OH)2 at various time spans of 1, 3 and 5 h over alkali-etched ZIF-67 via facile strategy. The optimum Ni(OH)2@etched ZIF-67 (5 h) (NEZ-3) heterostructure demonstrates excellent OER and UOR performance with a lower overpotential of 240 mV and 1.32 V, respectively at 10 mA cm−2. Moreover, the NEZ-3 electrocatalyst attains smaller Tafel values of 106 and 35 mV dec−1 with remarkable stability of 60 and 48 h for OER/UOR performance at 10 mA cm−2. Specifically, the two-cell electrolyzer requires a lower cell voltage of 1.73 V (OER) and 1.48 V (UOR) with an excellent durability of 20 h at 10 mA cm−2, respectively. Additionally, the water displacement method is used to examine the 4-electron transfer process (OER) of NEZ-3 electrocatalyst with a Faradaic efficiency of 87.53 %. Notably, the porous structure, introduction of oxygen defects (Ov), higher oxidation state of Ni3+, and abundant active sites in NEZ-3 electrocatalyst are the foremost reasons for the superior electrocatalytic water and urea oxidation reactions. Therefore, this research work delivers a simple methodology in emerging a highly active, stable, and cost-effective multifunctional electrocatalysts towards energy conversion applications.