An Economical and Scalable Method to Synthesize Graphitic-Like Films

Application of Hydrogenated Graphitic Supports in Electrocatalysts: Effects on Carbon Support Surface Chemistry, Nanoparticle Growth, and Electrocatalytic Activity

One of the key technical challenges before the widespread adoption of proton exchange membrane fuel cells (PEMFCs) is increasing the durability of the platinum catalyst layer to meet a target of 8000 operating hours with only a 10% loss of performance. Carbon corrosion, one of the primary mechanisms of degradation in fuel cells, has attracted attention from researchers interested in solving the durability problem. As such, the development of catalyst supports to avoid this issue has been a focus in recent years, with interest in hydrophobic supports such as highly graphitized carbons. In this research, we propose a method to increase the durability of carbon supports by way of exploiting hydrogenated graphene's hydrophobic properties. By performing a Birch reduction on graphene nanoplatelets, we were able to synthesize hydrogenated graphene nanoplatelets which were used as support for hollow porous PtNi nanoparticles. The structure of these nanoparticle-carbon composites was characterized by transmission electron microscopy (TEM), energy dispersive spectroscopy coupled with scanning transmission electron microscopy (STEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). We found that hydrogenation can strongly affect the morphology of nanoparticles formed as well as increase the electrochemical stability of the composites. Accelerated stress tests for 6000 cycles between 1.0 and 1.6 V vs RHE at 25 °C demonstrated that a hydrogenated support for PtNi increased the retained electrochemical surface from 36.8% to 61.9% when compared to the pristine graphene nanoplatelets. Moreover, the retained activity was increased from 26.6% to 53.0% by use of the hydrogenated carbon support. To confirm that hydrogenation enhanced durability, stress tests combined with Raman spectroscopy showed minimal change in the ID/IG ratio of the hydrogenated composite. Finally, identical location transmission electron microscopy (IL-TEM) was used to support the results of the electrochemical stress tests.

Dynamics of reduced graphene oxide: synthesis and structural models

Technological advancements are leading to an upsurge in demand for functional materials that satisfy several of humankind's needs. In addition to this, the current global drive is to develop materials with high efficacy in intended applications whilst practising green chemistry principles to ensure sustainability. Carbon-based materials, such as reduced graphene oxide (RGO), in particular, can possibly meet this criterion because they can be derived from waste biomass (a renewable material), possibly synthesised at low temperatures without the use of hazardous chemicals, and are biodegradable (owing to their organic nature), among other characteristics. Additionally, RGO as a carbon-based material is gaining momentum in several applications due to its lightweight, nontoxicity, excellent flexibility, tuneable band gap (from reduction), higher electrical conductivity (relative to graphene oxide, GO), low cost (owing to the natural abundance of carbon), and potentially facile and scalable synthesis protocols. Despite these attributes, the possible structures of RGO are still numerous with notable critical variations and the synthesis procedures have been dynamic. Herein, we summarize the highlights from the historical breakthroughs in understanding the structure of RGO (from the perspective of GO) and the recent state-of-the-art synthesis protocols, covering the period from 2020 to 2023. These are key aspects in the realisation of the full potential of RGO materials through the tailoring of physicochemical properties and reproducibility. The reviewed work highlights the merits and prospects of the physicochemical properties of RGO toward achieving sustainable, environmentally friendly, low-cost, and high-performing materials at a large scale for use in functional devices/processes to pave the way for commercialisation. This can drive the sustainability and commercial viability aspects of RGO as a material.