Electro-Oxidation of Metal Oxide-Fabricated Graphitic Carbon Nitride for Hydrogen Production via Water Splitting

Abstract

Hydrogen is a great sourcez of energy due to having zero emission of carbon-based contents. It is found primarily in water, which is abundant and renewable. For electrochemical splitting of water molecules, it is necessary to use catalytic materials that minimize energy consumption. As a famous carbon material, graphitic carbon nitride, with its excellent physicochemical properties and diversified functionalities, presents great potential in electrocatalytic sensing. In the present work, graphitic carbon nitride-fabricated metal tungstate nanocomposites are synthesized by the hydrothermal method to study their applications in catalysis, electrochemical sensing, and water splitting for hydrogen production. Nanocomposites using different metals, such as cobalt, manganese, strontium, tin, and nickel, were used as a precursor are synthesized via the hydrothermal process. The synthesized materials (g-C3N4/NiWO4, g-C3N4/MnWO4, g-C3N4/CoWO4, g-C3N4/SnWO4, g-C3N4/SrWO4) were characterized using different techniques, such as FTIR and XRD. The presence of a functional groups between the metal and tungstate groups was confirmed by the FTIR spectra. All the nanocomposites show a tungstate peak at 600 cm−1, while the vibrational absorption bands for metals appear in the range of 400–600 cm−1. X-ray diffraction (XRD) shows that the characteristic peaks matched with the JCPDS in the literature, which confirmed the successful formation of all nanocomposites. The electrochemical active surface area is calculated by taking cyclic voltammograms of the potassium–ferrocyanide redox couple. Among the entire series of metal tungstate, the g-C3N4/NiWO4 has a large surface area owing to the high conductive properties towards water oxidation. In order to study the electrocatalytic activity of the as-synthesized materials, electrochemical water splitting is performed by cyclic voltammetry in alkaline medium. All the synthesized materials proved to be efficient catalysts with enhanced conductive properties towards water oxidation. Among the entire series, g-C3N4-NiWO4 is a very efficient electrocatalyst owing to its higher active surface area and conductive activity. The order of electrocatalytic sensing of the different composites is: g-C3N4-NiWO4 > g-C3N4-SrWO4 > g-C3N4-CoWO4 > g-C3N4-SnWO4 > g-C3N4-MnWO4. Studies on electrochemically synthesized electrocatalysts revealed their catalytic activity, indicating their potential as electrode materials for direct hydrogen evolution for power generation.

Empowering the Nickel Iron Oxyhydroxide through a Heterostructure Cocatalyst for Superior Alkaline and Saline Water Reduction

“…Addition of heterostructures over the layered hydroxides provides active charge transfer ability, interacting surface area, and specified catalytic activity with refined selectivity. 8,22−24 Ashfaq et al 25 demonstrated that composites of g-C 3 N 4 with NiA x O 4 enhance the active surface area for interacting species. The porosity in the g-C 3 N 4 enriches the adsorbing area for the decorating particles.…”

“…In an electrolyzer, to regulate the charge transfer (e – ) between the working electrode and electrolyte, the working electrode is typically developed with surface and interfacial modifications such as the addition of dopant or composites and decoration of heterostructures over the working electrode. Addition of heterostructures over the layered hydroxides provides active charge transfer ability, interacting surface area, and specified catalytic activity with refined selectivity. ,− Ashfaq et al demonstrated that composites of g-C 3 N 4 with NiA x O 4 enhance the active surface area for interacting species. The porosity in the g-C 3 N 4 enriches the adsorbing area for the decorating particles. , Xia et al found that the addition of silver sulfide (Ag-Ag 2 S) as a composite material in molybdenum disulfide (MoS 2 ) enhances the reaction kinetics in HER.…”