Newly Designed Graphene Cellular Monolith Functionalized with Hollow Pt-M (M = Ni, Co) Nanoparticles as the Electrocatalyst for Oxygen Reduction Reaction

Abstract

Newly designed graphene cellular monoliths (GCMs) functionalized with hollow Pt-M nanoparticles (NPs) (Pt-M/GCM, M = Ni, Co) have been successfully achieved by a facile and powerful method on the basis of sonochemical-assisted reduction and gelatinization processes. First, hollow Pt-M (M = Ni, Co) NPs were synthesized and distributed on graphene oxide sheets (Pt-M/GO) by sodium borohydride reduction of metal precursors in the ultrasonic environment. Second, the hollow structure was further formed by ascorbic acid (AA) reduction of Pt precursors in gelatinization process. Meanwhile, GO sheets with hollow Pt-M NPs were reduced to graphene, and were assembled into Pt-M/GCM hydrogels by gelatinization process. The Pt-M/GCM (M = Ni, Co) electrocatalysts have a factor of 9.4-18.9 enhancement in electrocatalytic activity and higher durability toward oxygen reduction reaction (ORR), compared with those of commercial Pt/C catalyst. In detail, the mass activities for Pt-Ni/GCM and Pt-Co/GCM are 1.26 A mg and 1.79 A mg, respectively; meanwhile, the corresponding specific activities are 1.03 and 2.08 mA cm. The successful synthesis of such attractive materials paves the way to explore a series of porous materials in widespread applications.

Isolated Fe Single Atomic Sites Anchored on Highly Steady Hollow Graphene Nanospheres as an Efficient Electrocatalyst for the Oxygen Reduction Reaction

“…[1,2] The sluggish 4-electroninvolved kinetics and high overpotential of cathodic ORR greatly restrict the energy-conversion efficiency and remain primary technical challenges hampering the widespread commercialization of these ORR-involved devices. [5,6] In this context, the development of cost-effective, ultrastable, and highefficiency earth-abundant metal catalysts which can substitute PGM is extremely urgent and thereby has stimulated tremendous research interests in renewable energy field. [5,6] In this context, the development of cost-effective, ultrastable, and highefficiency earth-abundant metal catalysts which can substitute PGM is extremely urgent and thereby has stimulated tremendous research interests in renewable energy field.…”

Active Sites Derived from Heteroatom Doping in Carbon Materials for Oxygen Reduction Reaction

“…Furthermore, hollow Pt─M (M = Ni, Co) nanoparticle-decorated graphene was designed as an electrocatalyst for the ORR. Due to the hollow interior, the amount of buried nonfunctional precious metal atoms decreased and hence enhanced the electrocatalytic activity and durability toward the ORR [7]. Based on the same mechanism, a hollow structure of a Pt catalyst was also reported by Li and co-workers.…”

“…Earlier studies have focused on tuning the surface structure [6][7][8] and electronic structure [9] of Pt as well as the electrocatalyst supports [10,11] to achieve optimum ORR activity by using the least amount of Pt. In addition, various kinds of catalysts, including transition metals and their alloys, transition metal oxides/nitrides/sulfides, as well as mixed-valence metal oxides [12,13], carbon-based metal-free catalysts [14], and others have been developed to promote the sluggish kinetics of the ORR at the cathode.…”

Rational Design of Fe1−xS/Fe3O4/Nitrogen and Sulfur‐Doped Porous Carbon with Enhanced Oxygen Reduction Reaction Catalytic Activity

“…Among the catalysts that have been studied, carbon materials have a wide range of applications due to their high electrocatalytic activity, chemical stability, and structural diversity. In particular, heteroatom doping is essential to achieve excellent ORR activity . For example, transition metals such as Fe, Co, Ni, and Cu, display fairly strong oxygen adsorption in ORR, which can enhance the ORR activity .…”