Construction and Regulation of a Surface Protophilic Environment to Enhance Oxygen Reduction Reaction Electrocatalytic Activity

Abstract

Pyrolytic transition metal nitrogen–carbon (M–N/C) materials are considered as the most promising alternatives for platinum-based catalysts toward oxygen reduction reaction (ORR). As the proton-coupled electron transfer step in ORR has been proven to be a rate-determining step in the M–N/C catalysts, we envisaged that building a protophilic surface might be helpful to enhance the ORR activity. Herein, a polyaniline decoration strategy was put forward and realized to confer the Fe–N/C catalyst with a surface protophilic environment. A 20 mV positive shift in half-wave potential was observed owing to the enriched interfacial proton concentration, corresponding to a tripled turnover frequency under acidic conditions (from 0.46 to 1.28 e·s–1·sites–1). Our work blazed a new path toward the design of M–N/C ORR catalysts, commencing via the ORR kinetics.

Fe, B, and N Codoped Carbon Nanoribbons Derived from Heteroatom Polymers as High-Performance Oxygen Reduction Reaction Electrocatalysts for Zinc–Air Batteries

“…Notably, the introduction of B in Fe–N–C led to a larger C dl compared to that in Fe–N–C (10.30 mF cm –2 ), which indicated that B doped in the carbon matrix can introduce more active sites for ORR. We further calculated the TOF values for each Fe site on Fe–B–N–C and Fe–N–C to elucidate the effect of the B dopant. , The TOFs of Fe–B–N–C and Fe–N–C are 4.63 and 2.96 e·s –1 ·sites –1 , respectively, proving that B doping can improve the turnover frequency of Fe sites. In addition, KSCN was used to poison Fe sites to explore the role of Fe species in ORR. , As shown in Figure S11, when 10 mM KSCN was added to the electrolyte, the half-wave potential of Fe–B–N–C decreased by 40 mV and the limiting current density decreased by 0.463 mA cm –2 , proving that Fe sites played an important role in the catalytic process.…”

“…Notably, the introduction of B in Fe−N−C led to a larger C dl compared to that in Fe−N−C (10.30 mF cm −2 ), which indicated that B doped in the carbon matrix can introduce more active sites for ORR. We further calculated the TOF values for each Fe site on Fe−B−N−C and Fe−N−C to elucidate the effect of the B dopant 65,66. The TOFs of Fe−B− N−C and Fe−N−C are 4.63 and 2.96 e•s −1 •sites −1 , respectively, proving that B doping can improve the turnover frequency of Fe sites.…”

Effect of Nitrogen-Containing Carbon Shell-Coated Carbon Support on the Catalytic Performance of Platinum–Cobalt Alloy Catalyst for Oxygen Reduction

“…The transmission electron microscope (TEM) images of carbon black and C@NC are shown in Figure a,b where the nitrogen-doped carbon shell is difficult to distinguish due to the similar contrast between the nitrogen-doped carbon shell prepared by pyrolysis of PANI and the catalyst carbon matrix . However, by comparing the carbon blacks before and after coating, we noticed a slight increase in particle size, which corresponds to the carbon support surface being covered by a carbon–nitrogen shell.…”

Metal–Organic Frameworks (MOFs) Derived Materials Used in Zn–Air Battery

“…Fe-N-C catalysts have the highest ORR activity among M-N-C (M = transition metal) [ 75 , 76 , 77 ]. However, there are few reports on the direct pyrolysis of Fe-MOF materials for oxygen redox reaction.…”