Nitrogen Functionalization of CVD Grown Three-Dimensional Graphene Foam for Hydrogen Evolution Reactions in Alkaline Media

Daniela Ion-Ebrașu; Radu Dorin Andrei; Stanică Enache; Simona Căprărescu; Constantin Cătălin Negrilă; Cătălin Jianu; Adrian Enache; Iulian Boerașu; Elena Carcadea; Mihai Varlam; Bogdan Ștefan Vasile; Jianwei Ren

doi:10.3390/ma14174952

Nitrogen Functionalization of CVD Grown Three-Dimensional Graphene Foam for Hydrogen Evolution Reactions in Alkaline Media

Materials (Basel). 2021 Aug 30;14(17):4952. doi: 10.3390/ma14174952.

Affiliations

¹ National Institute for Cryogenics and Isotopic Technologies ICSI-Rm. Valcea, ICSI Energy, Uzinei Street, No. 4, 240050 Ramnicu Valcea, Romania.
² Inorganic Chemistry, Physical Chemistry and Electrochemistry Department, Faculty of Applied Chemistry and Materials Science, University POLITEHNICA of Bucharest, Gh. Polizu Street, No. 1-7, 011061 Bucharest, Romania.
³ National Institute for Materials Physics, P.O. Box MG-7, 77125 Bucharest, Romania.
⁴ National Research Center for Micro and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University POLITEHNICA of Bucharest, Splaiul Independentei Street, No. 313, 060042 Bucharest, Romania.
⁵ Department of Mechanical Engineering Science, University of Johannesburg, Cnr Kingsway and University Roads, Auckland Park, Johannesburg 2092, South Africa.

Abstract

Three-dimensional graphene foam (3D-GrFoam) is a highly porous structure and sustained lattice formed by graphene layers with sp² and sp³ hybridized carbon. In this work, chemical vapor deposition (CVD)-grown 3D-GrFoam was nitrogen-doped and platinum functionalized using hydrothermal treatment with different reducing agents (i.e., urea, hydrazine, ammonia, and dihydrogen hexachloroplatinate (IV) hydrate, respectively). X-ray photoelectron spectroscopy (XPS) survey showed that the most electrochemically active nitrogen-doped sample (GrFoam3N) contained 1.8 at % of N, and it exhibited a 172 mV dec^-1 Tafel plot associated with the Volmer-Heyrovsky hydrogen evolution (HER) mechanism in 0.1 M KOH. By the hydrothermal process, 0.2 at % of platinum was anchored to the graphene foam surface, and the resultant sample of GrFoamPt yielded a value of 80 mV dec^-1 Tafel associated with the Volmer-Tafel HER mechanism. Furthermore, Raman and infrared spectroscopy analysis, as well as scanning electron microscopy (SEM) were carried out to understand the structure of the samples.

Keywords: chemical vapor deposition; graphene; hydrogen evolution reaction; nitrogen-doping.