A Ru-doping and conductive metal-organic-framework co-modification strategy for enhanced full water splitting performance of a CoCu-LDH nanosheet array

Abstract

Extensive research interest has been focused on how to promote the electrocatalytic performance of transition-metal layered double hydroxides (LDHs) for water splitting. Here, we designed a heteroatom-doping and conductive metal-organic framework (cMOF) co-modification strategy to successfully construct a Ru-doped CoCu-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene)/CoCu-LDH nanosheet array on a Cu foam substrate (labeled as CoCuRu-HHTP/CoCuRu-LDH). Electrochemical measurements showed that CoCu-LDH, CoCuRu-LDH, CoCu-HHTP/CoCu-LDH and CoCuRu-HHTP/CoCuRu-LDH separately required an overpotential of 204 mV, 175 mV, 69 mV, and 27 mV to deliver a current density of -10 mA cm-2 for the HER and 345 mV, 216 mV, 275 mV, and 204 mV to reach a current density of 10 mA cm-2 for the OER in 1 M KOH solution. The above facts clearly demonstrate that the present co-modification strategy significantly enhances the electrocatalytic water splitting performance of CoCu-LDH. In a two-electrode setup using the as-prepared CoCuRu-HHTP/CoCuRu-LDH nanosheet array as the cathode and anode simultaneously, only a cell voltage of 1.48 V was required to deliver a current density of 10 mA cm-2, which is comparable to that of pure noble metal-based materials and surpasses that of most reported MOF-based catalysts.