Nitrogen and Phosphorus Dual-Doped Graphene/Carbon Nanosheets as Bifunctional Electrocatalysts for Oxygen Reduction and Evolution

Abstract

It is highly desirable but challenging to develop bifunctional catalysts for efficiently catalyzing both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in energy storage and conversion system. Here a simple yet cost-effective strategy is developed to fabricate nitrogen and phosphorus dual-doped graphene/carbon nanosheets (N,P-GCNS) with N,P-doped carbon sandwiching few-layer-thick graphene. The as-prepared N,P-GCNS shows outstanding catalytic activity towards both ORR and OER with a potential gap of 0.71 V between the OER potential at a current density of 10 mA cm -2 and the ORR potential at a current density of -3 mA cm -2 , illustrating that it is the best metal-free bifunctional electrocatalysts reported to date. The superb bifunctional catalytic performance is attributed to the synergistic effects between the doped N and P atoms, the full exposure of the active sites on the surface of the N,P-GCNS nanosheets, the high conductivity of the incorporated graphene, the large surface area and hierarchical pores for sufficient contact and rapid transportation of the reactants.

Carbon Solving Carbon's Problems: Recent Progress of Nanostructured Carbon‐Based Catalysts for the Electrochemical Reduction of CO2

“…With the success of single doped carbons for CO 2 RR applications, multiple heteroatom doping strategies could also prove to be feasible for enhancing catalytic activity, as seen for other electrochemical processes. [57,58] However, such strategies have yet to be employed for carbon-based CO 2 RR electrocatalysts.…”

A Library of Doped-Graphene Images via Transmission Electron Microscopy

“…By this strategy, the metal carbonate dopants increased the electron concentration in pristine graphene through the covalent bond, thereby reducing the work function [45]. A simple and effective strategy to fabricate N-P co-doped graphene/carbon nanosheets (N,P-GCNS) by pyrolysis of a dried hydrogel composed of GO, polyaniline (PANi), and phytic acid (PA), where GO nanosheets were employed as the precursor of graphene and the structure directing agents A simple and effective strategy to fabricate N-P co-doped graphene/carbon nanosheets (N,P-GCNS) by pyrolysis of a dried hydrogel composed of GO, polyaniline (PANi), and phytic acid (PA), where GO nanosheets were employed as the precursor of graphene and the structure directing agents for conformal coating of PANi and PA molecules during polymerization of aniline (An) monomers (Figure 14a) [76]. The porous sheet-like structure of N,P-GCNS material was confirmed by low magnification-TEM image with the observed corrugations (Figure 14b).…”

Straightforward synthesis of nitrogen-doped carbon nanotubes as highly active bifunctional electrocatalysts for full water splitting

“…However, developing such active bifunctional electrocatalysts is challenging due to the incompatibility of pH ranges in which catalysts are stable and active. In this view, various efficient bifunctional catalysts based on transition-metal based compounds of Ni [6,8,[17][18][19][20], Co [4,16,21] and doped heteroatoms [22][23][24] in alkaline media have been proposed. However, the transition metal oxide materials suffer from intrinsically low conductivity limiting their performance at high current densities.…”

“…Such carbon supports are inactive toward most of the electrochemical reactions. However, the graphite or carbonaceous materials can be doped by heteroatoms such as nitrogen [24,27], boron [28] or phosphorous [22] to form active metal-free electrocatalysts. Carbonaceous doped materials can be used either as metal-free electrocatalysts [29,30] or as catalyst supports [31] for active metal nanoparticles to get the advantage of synergistic catalytic activity.…”