Co Nanoparticles/Co, N, S Tri-doped Graphene Templated from In-Situ-Formed Co, S Co-doped g-C₃N₄ as an Active Bifunctional Electrocatalyst for Overall Water Splitting

Abstract

The development of high-performance electrocatalyst with earth-abundant elements for water-splitting is a key factor to improve its cost efficiency. Herein, a noble metal-free bifunctional electrocatalyst was synthesized by a facile pyrolysis method using sucrose, urea, Co(NO) and sulfur powder as raw materials. During the fabrication process, Co, S co-doped graphitic carbon nitride (g-CN) was first produced, and then this in-situ-formed template further induced the generation of a Co, N, S tri-doped graphene coupled with Co nanoparticles (NPs) in the following pyrolysis process. The effect of pyrolysis temperature (700, 800, and 900 °C) on the physical properties and electrochemical performances of the final product was studied. Thanks to the increased number of graphene layer encapsulated Co NPs, higher graphitization degree of carbon matrix and the existence of hierarchical macro/meso pores, the composite electrocatalyst prepared under 900 °C presented the best activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with outstanding long-term durability. This work presented a facile method for the fabrication of non-noble-metal-based carbon composite from in-situ-formed template and also demonstrated a potential bifunctional electrocatalyst for the future investigation and application.

Cobalt Entrapped in N,S‐Codoped Porous Carbon: Catalysts for Transfer Hydrogenation with Formic Acid

“…For S (Figure c), the typical thiophene‐S peaks arising from S 2p 3/2 (163.8 eV) and S 2p 1/2 (165.0 eV) multiplets were observed, together with SO x centered at approximately 167.2 and 168.8 eV . Specifically, there was no peak at a binding energy of approximately 162.4 eV, which is usually attributed to the Co−S bond, indicating no generation of cobalt sulfide in the samples of Co‐NSPC‐850 or direct Co–S interaction . The spectrum of Co 2p 3/2 was composed of four peaks (Figure d).…”

“…[48] Specifically,t here was no peak at ab inding energy of approximately 162.4 eV,w hich is usually attributed to the CoÀSb ond, indicating no generation of cobalt sulfide in the samples of Co-NSPC-850 or direct Co-S interaction. [49] The spectrum of Co 2p 3/2 was composed of four peaks (Figure2d). The energy peak at 778.4 eV wasa ttributed to metallic Co 0 ,c orresponding to the TEM and XRD results.…”

Ultrathin Two‐Dimensional Metal‐Organic‐Framework‐Derived CoO/Nitrogen and Sulfur Co‐doped Ultrathin Porous Carbon Nanoplates for Highly Efficient Water Electrolysis

“…With the cell potential increasing from 1.46 V to 1.63 V, the current of water electrolysis also increases from 0 to 10 mA cm −2 , and numerous H 2 and O 2 bubbles are produced from the surface of the carbon cloth (the inset in Figure a). This potential can be competitive with some other Co‐based water electrolyzers (Figure c) . The stability test (Figure b) shows that the cell potential only increases 30 mV after continuous testing at 10 mA cm −2 for 20 h, indicating a high stability.…”

“…The surface area and pore volume of the CoO/N‐S‐UPCNPs‐600 are 636.1 m 2 g −1 and 1.22 cm 3 g −1 , larger than those of the CoO/N‐S‐UPCNPs‐500 (319.0 m 2 g −1 and 0.69 cm 3 g −1 ) and −700 (497.9 m 2 g −1 and 1.01 cm 3 g −1 ). The larger surface area and pore volume will make the exposure of catalytic sites and make mass transfer easier in the process of water electrolysis . Therefore, the CoO/N‐S‐UPCNPs‐600 can be expected to display higher electrocatalytic performance compared with the other two samples.…”

Hierarchically Porous Co/CoxMy (M = P, N) as an Efficient Mott–Schottky Electrocatalyst for Oxygen Evolution in Rechargeable Zn–Air Batteries

“…Notwithstanding significant progress, massive efforts mainly focused on coupling metal with a single semiconductor, which limits the electrocatalytic performance of Mott–Schottky catalysts to a certain extent. In other words, by codoping two or more metal‐semiconductors into transition metals, forming Co/Co x M y (M = P, N, or S) is more attractive for the electrocatalysis due to the multiple synergistic effects between different metal‐semiconductors by creating a unique electronic structure . To date, the multicomponent Co/Co x M y has been rarely reported for the electrocatalysis.…”