Dual Single‐Atomic Ni‐N₄ and Fe‐N₄ Sites Constructing Janus Hollow Graphene for Selective Oxygen Electrocatalysis

Abstract

Nitrogen coordinated metal single atoms in carbon have aroused extensive interest recently and have been growing as the active research frontier in a wide range of key renewable energy reactions and devices. However, single-atom catalysts with isolated metallic active components cannot satisfy the demand of electrocatalysis with the requirement in selectivity. Herein, we develop a step-by-step self-assembly strategy to allocate nickel (Ni) and iron (Fe) single atoms respectively on the inner and outer walls of graphene hollow nanospheres (GHSs), for the first time realizing the separate-sided different single-atom functionalization of hollow graphene. The Ni or Fe single atom is demonstrated to be coordinated with four N atoms via the formation of a Ni-N 4 or Fe-N 4 planar experimental observations. As a proof-of-concept demonstration for realistic application, the Ni-N 4 /GHSs/Fe-N 4 endows the rechargeable Zn-air battery with excellent energy efficiency and cycling stability as an air-cathode, outperforming the performance of benchmark Pt/C+RuO 2 air-cathode. The current work paves a new avenue for precise control of single-atom sites on carbon surface for the high-performance and selective electrocatalysts.

Low‐Load Pt Nanoclusters Anchored on Graphene Hollow Spheres for Efficient Hydrogen Evolution

“…First, PtCl 4 2− was adsorbed onto the positively charged SiO 2 nanosphere (Figure S1, Supporting Information) through the electrostatic action to obtain SiO 2 @PtCl 4 2− . [ 39 ] Then, the negatively charged graphene oxide nanosheets are coated onto the SiO 2 @PtCl 4 2− to obtain SiO 2 @PtCl 4 2− @GO. The obtained SiO 2 @PtCl 4 2− @GO was calcined under high temperature in N 2 atmosphere, in which the divalent Pt was reduced to Pt nanoclusters by the carbon contained in graphene.…”

Interface Engineering of Air Electrocatalysts for Rechargeable Zinc–Air Batteries

“…The image representing synergistic effect is reproduced with permission. [ 87 ] Copyright 2020, Wiley‐VCH. The image representing confinement effect is reproduced with permission.…”

“…Reproduced with permission. [ 87 ] Copyright 2020, Wiley‐VCH. e) Illustration of the proposed OER mechanism based on synergistic effect.…”

“…have proposed a bifunctional Janus catalyst via selective combining of the single atom Fe sites and Ni sites. [ 87 ] As shown in Figure 7d, the outer Fe sites were responsible for ORR reaction while inner Ni sites were OER active. And comparing with benchmark Pt/C+RuO 2 , which was just simply mixing, the effective interface engineering ensured the tight contact of Ni/Fe‐based configurations on hollow graphene.…”

Hollow Carbon Nanocubes as Oxygen Reduction Reaction Electrocatalyst

“…However, during discharge process, the fuel batteries are involved with 4 e − oxygen reduction reaction (ORR) with sluggish kinetics, which needs effective electrocatalysts to overcome the large overpotential [4–5] . As the most effective ORR catalyst, Pt possesses favorable electronic structure with intrinsic activity, while the limited resource and high cost imped its large‐scale application [6–8] . Thus, investigating efficient non‐noble metal electrocatalysts to accelerate ORR kinetics is highly desired [9–11] …”