Enhancing the Hydrogen and Oxygen Evolution Reaction Efficiency of Amine Functionalized MOF NH-UiO-66 via Incorporation of CuO Nanoparticles

Abstract: Development of highly efficient and stable bi-functional electrocatalyst towards both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) by engaging the earth abundant precursors has attracted much research attention. In this study, a highly efficient, durable and stable amine functionalized MOF based bi-functional electrocatalyst CuO@NH-UiO-66 has been facilely synthesized via in-situ incorporation of pre-synthesized CuO nanoparticles into amine functionalized Zr-MOF NH-UiO-66. It is observed that CuO@NH-UiO-66 exhibits excellent bi-functional electrocatalytic activity towards HER as well as OER and delivers the benchmark of 10 mA cm current density at just 166 and 283 mV overpotential, respectively, which is better than several previously, reported Cu-based, different transition metals and MOF based HER and OER catalysts. It also exhibits lower Tafel slope value 87 and 113 mV dec towards HER and OER, respectively which indicates faster and better charge transfer during catalytic activity. CuO@NH-UiO-66 exhibits significant stability and generates constant current density upto 6000 s during water electrolysis experiments. Furthermore, SEM and P-XRD techniques are used to investigate the stability of working electrode after the electrocatalytic studies and it is observed that CuO@NH-UiO-66 maintains its integrity and chemical structure, after many hours of electrocatalytic activity. This study encourages the development of more earth abundant transition metals and MOFs based electrocatalysts for efficient electrochemical studies. Graphic Abstract: [Figure not available: see fulltext.]