Doping Ir/Ru and comparing electrocatalytic activity of cobalt metal organic framework (MOF) and Co3O4: Enhanced bifunctional and overall water splitting activity

Exploring methods for improving the electrocatalytic water splitting activity of functional metal organic frameworks (MOFs) has received significant attention in recent years. Herein, we presented Ir/Ru doping approach to improve the bifunctional electrocatalytic activity of cobalt-benzene dicarboxylic acid (CoTPA) MOF and further compared with the Co 3 O 4 derived from the corresponding MOFs. The undoped CoTPA required the overpotential of 286 and 269 mV for producing 10 mA/cm 2 current density in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. In contrast, Ir-CoTPA-250 required 255 and 175 mV overpotential whereas Ru-CoTPA-250 needed 247 and 213 mV in OER and HER, respectively. However, the conversion of CoTPA MOF into Ir/Ru doped Co 3 O 4 (Ir-CoTPA-450 and Ru-CoTPA-450) reduced the electrocatalytic activity . The mechanistic studies indicated that Ir/Ru doping reduced the Tafel slope and charge transfer resistance in Ir/Ru-CoTPA-250 and further supported the enhanced electrocatalytic activity. The strong bifunctional electrocatalytic activity of Ir/Ru-CoTPA-250 was also utilized for overall water splitting . Ir-CoTPA-250 and Ru-CoTPA-250 required the cell voltage of 1.66 and 1.69 V to produce 10 mA/cm 2 current density. Thus, the present work indicated the possibility of improving MOFs electrocatalytic activity by trace amount doping of noble metal ions . Ir/Ru doped CoTPA MOF exhibited significantly stronger electrocatalytic bifunctional (OER and HER) and overall water splitting activity in alkaline medium compared to Ir/Ru doped Co 3 O 4 . • Enhancing bifunctional electrocatalytic activity of CoTPA MOF via Ir/Ru doping. • Comparing the electrocatalytic activity of Ir/Ru doped CoTPA MOF and Co 3 O 4 (MOF derived metal oxides). • Ir-CoTPA-250 required only 175 mV overpotential whereas Ir doped Co 3 O 4 required 285 mV for 10 mA/cm 2 current density in HER. • A strong overall water splitting electrocatalyst (1.66 V for 10 mA/cm 2 ) with good stability.