Electrocatalytic activity of Cu-3,4-dihydroxybenzoic (Cu/DHB), Co/Tb-3-amino-4-hydroxybenzoic (Co/AHB, Tb/AHB) metal organic framework supported reduced graphene oxide (rGO) for oxygen reduction reaction (ORR)

Electrocatalytic activities of three MOFs based on two similar benzoate derivative ligands and transition metal or lanthanide ions, namely {[Co(3a4obenz)]center dot 0.5DMF center dot H2O}(n) (1(Co)), {[Cu-3(3o4obenz)(2)(DMF)(2)]center dot 3H(2)O}(n) (2(Cu)) and {[Tb-5(3a4obenz)(6)(OH)(3)(DMF)(3)]center dot 5H(2)O}(n) (3(Tb)), where 3a4obenz = 3-amino-4-oxobenzoato and 3o4obenz = 3,4dioxobenzoato have been investigated. In addition to their properties in bulk state, these MOFs have been also supported on reduced graphene oxide (rGO). The deposited MOFs present improved electrocatalytic performance than bulk samples, among which 1(Co)@rGO presents the best electrocatalytic activity and also exhibits a high selectivity and superior tolerance towards methanol crossover effects. The ratio of MOF supported on rGO has been concisely studied to optimize the performance of the oxygen reduction reaction (ORR), finding that 1(Co)/rGO in a 3:7 ratio (w/w) shows the best results with 3.73 electrons transferred (n) at 0.7 V (maximum of n = 3.83 at 0.8 V), Tafel slope of 118 mV/dec, onset potential of 0.93 V vs RHE, and the best stability among other compositions.

Automated summary

The electrocatalytic activities of three MOFs based on similar benzoate derivative ligands and transition metal or lanthanide ions have been studied. The MOFs supported on reduced graphene oxide exhibit improved electrocatalytic performance, with 1(Co)@rGO showing the best activity and selectivity towards methanol crossover effects. The ratio of MOF supported on rGO was also studied to optimize the performance of the oxygen reduction reaction, with 1(Co)/rGO in a 3:7 ratio showing the best results.