Graphene Supported Rhodium Nanoparticles for Enhanced Electrocatalytic Hydrogen Evolution Reaction

Abstract

Current research on catalysts for proton exchange membrane fuel cells (PEMFC) is based on obtaining higher catalytic activity than platinum particle catalysts on porous carbon. In search of a more sustainable catalyst other than platinum for the catalytic conversion of water to hydrogen gas, a series of nanoparticles of transition metals viz., Rh, Co, Fe, Pt and their composites with functionalized graphene such as RhNPs@f-graphene, CoNPs@f-graphene, PtNPs@f-graphene were synthesized and characterized by SEM and TEM techniques. The SEM analysis indicates that the texture of RhNPs@f-graphene resemble the dispersion of water droplets on lotus leaf. TEM analysis indicates that RhNPs of <10 nm diameter are dispersed on the surface of f-graphene. The air-stable NPs and nanocomposites were used as electrocatalyts for conversion of acidic water to hydrogen gas. The composite RhNPs@f-graphene catalyses hydrogen gas evolution from water containing p-toluene sulphonic acid (p-TsOH) at an onset reduction potential, Ep, −0.117 V which is less than that of PtNPs@f-graphene (Ep, −0.380 V) under identical experimental conditions whereas the onset potential of CoNPs@f-graphene was at Ep, −0.97 V and the FeNPs@f-graphene displayed onset potential at Ep, −1.58 V. The pure rhodium nanoparticles, RhNPs also electrocatalyse at Ep, −0.186 V compared with that of PtNPs at Ep, −0.36 V and that of CoNPs at Ep, −0.98 V. The electrocatalytic experiments also indicate that the RhNPs and RhNPs@f-graphene are stable, durable and they can be recycled in several catalytic experiments after washing with water and drying. The results indicate that RhNPs and RhNPs@f-graphene are better nanoelectrocatalysts than PtNPs and the reduction potentials were much higher in other transition metal nanoparticles. The mechanism could involve a hydridic species, Rh-H− followed by interaction with protons to form hydrogen gas.

Conformal Noble Metal High-Entropy Alloy Nanofilms by Atomic Layer Deposition for an Enhanced Hydrogen Evolution Reaction

“…The HER–LSV plots with wider scanning ranges are shown in Figure S3. A Rh single layer was selected as the control group because of its substantial potential for HER catalysis , and strong stability compared to other metals under diverse environments. − The Tafel slopes plotted in Figure b reveal the HER kinetics in 0.5 M H 2 SO 4 , where the values of 47, 59, and 42 mV/dec were calculated, respectively, for Rh, 5-layer, and HEA thin film. The lowest Tafel slope value indicates the HEA thin film had the fastest hydrogen production rate.…”

Silver Decorated Reduced Graphene Oxide as Electrocatalyst for Zinc–Air Batteries

“…Graphene is a two-dimensional monolayer of carbon atoms densely packed in a honeycomb crystal lattice [23]. As a promising material for next-generation energy storage and conversion devices, graphene has attracted tremendous attention because of its superior properties [24][25][26][27]. Graphene exhibits a unique two-fold advantage with remarkably high electron mobility at room temperature and fast heterogeneous electron transfer at the edges.…”

Preparation of Graphene Nanolayers through Surfactant-assisted Pure Shear Milling Method

“…Recently, the application of graphene has been gained increasing attention by researchers because of its unique properties [17][18][19][20][21]. Graphene, a single layer of graphite, is a basic block of sp 2 -bonded carbon for graphitic materials such as graphite [22][23][24][25], fullerene [26][27][28] and carbon nanotubes [29][30][31][32][33][34][35][36][37][38], which has both unique mechanical and physical properties making it a promising material for applications in nanotechnology [39][40][41][42][43][44]. A stable graphene sheet was discovered by Novoselov and Geim (2004) for the first time [45].…”