The oxygen reduction reaction (ORR) has a crucial function as the cathode reaction in energy-converting systems, such as fuel cells (FCs), which contributes to a sustainable energy supply. However, the current use of precious Pt-based electrocatalysts (ECs) is a major drawback for the economic viability of fuel cells. Hence, it is urgent to develop cost-effective and efficient electrocatalysts (ECs) without noble metals to substitute the Pt-based ECs. Herein, we report the preparation and application as ORR electrocatalysts of four new nanocomposites based on sandwich-type phosphotungstate (TBA)H[Co(HO)(PWO)] (TBA-Co(PW)) immobilized onto different carbon nanomaterials [single-walled carbon nanotubes (SWCNT), graphene flakes (GF), carbon nanotubes doped with nitrogen (N-CNT), and nitrogen-doped few layer graphene (N-FLG)]. In alkaline medium, the four nanocomposites studied presented comparable onset potentials (0.77-0.90 V vs RHE), which are similar to that observed for Pt/C (0.91 V vs RHE). Higher diffusion-limiting current densities ( j, = -168.3 mA cm mg) were obtained for Co(PW)@N-CNT, as compared to Pt/C electrode -130.0 mA cm mg) and the other ECs (-45.0, -50.7, and -87.5 mA cm mg for Co(PW)@SWCNT, Co(PW)@GF, and Co(PW)@N-FLG, respectively). All the Co(PW)@CM ECs showed selectivity toward direct O reduction to water with the exception of Co(PW)@GF where a mixture of the 2- and 4-electron mechanisms is observed. Furthermore, low Tafel slopes were obtained for all the nanocomposites (68-96 mV dec). Co(PW)@CM ECs also showed excellent tolerance to methanol with no significant changes in current density, in contrast to Pt/C (decrease of ≈59% after methanol addition) and good long-term electrochemical stability with current retentions between 75 and 84%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.