Ultrathin nanosheet metal–organic framework@NiO/Ni nanorod composites

Abstract

• The complex architectures were synthesized through simple procedures. • A low-dose HRTEM technique was utilized to visualize the complex architectures. • The ultrathin nanosheet Ni-MOF@NiO/Ni nanorods exhibited excellent UOR activities. • The superior catalytic activity arose from the strong synergistic effects between Ni-MOF and NiO/Ni. Two-dimensional metal–organic frameworks are a family of materials with great potential for electrocatalysis; however, these materials usually have the poor thermodynamic stability and require harsh preparation conditions. Here, we describe a facile approach for preparing ultrathin nanosheet metal–organic framework@NiO/Ni nanorods with increased stability and highly active sites compared with in case of pristine metal–organic frameworks. These peculiar hierarchical nanocomposites exhibit excellent properties for urea electrolysis, including abundant exposed active sites owing to their nanosheet-nanorod hierarchical structure, enriched Ni-species, and improved stability. The prepared composites demonstrate superior electrocatalytic performance toward the urea oxidation reaction with a low overpotential of only 170 mV to reach 10 mA cm −2 , a small Tafel slope of 48.1 mV dec -1 , and a low cell voltage of 1.42 V for overall urea electrolysis, with outstanding long-term durability (15,000 s with only 7.1% activity decay). This combination between metal–organic frameworks and materials with high thermodynamic stability offers a strategy for further development of excellent electrocatalysts.