First Principles Study of Noble Metal (Single Atom and Cluster) Decorated Reduced Graphene Oxide for Efficient Formaldehyde Adsorption

Abstract

This article presents a computational study on formaldehyde (HCHO) adsorption performances of noble metal (Pt, Au, and Ag) nanoparticles functionalized reduced graphene oxide (RGO). The molecular adsorption over all the RGO-metal hybrids with varying sizes of metal clusters (n = 2, 4, and 13) has been characterized in terms of changes in electronic structures, ground state energies and electron distributions of the respective materials upon HCHO adsorption. The density functional theory (DFT) based quantum simulation results reveal that the HCHO adsorption strength of the RGO-metal nanoparticle composite differs as per the sequence: RGO-Pt <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> > RGO-Au <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> > RGO-Ag <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sub> . The strongest adsorption affinity of platinum is primarily attributed to incomplete electron occupancy of valance dorbital (Pt-4d <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> ). While, relatively larger degree of closeness in sand d band energies makes Au a superior HCHO adsorbent over Ag. Single metal atom (n = 1) owing to have high energy and chemical reactivity produces enhanced values of adsorption energy and charge transfer which eventually saturate as the cluster size grows (n = 13). The influence of carbon vacancies (both single and double) of the underlying RGO sheet on HCHO adsorption process has also been examined. Observed results indicate that the vacancy defect has some unfavorable effects in binding molecule to all these metal decorated RGO structures irrespective of metal types and cluster sizes. Thus, the present computational work covering important practical aspects is expected to have great contribution to the exploration of HCHO adsorbing materials suitable for the development of RGO based resistive HCHO sensors.