Substrate engineering of graphene reactivity: towards high-performance graphene-based catalysts

Abstract

Graphene-based solid-state catalysis is an emerging direction in research on graphene, which opens new opportunities in graphene applications and thus has attracted enormous interests recently. A central issue in graphene-based catalysis is the lack of an effective yet practical way to activate the chemically inert graphene, which is largely due to the difficulties in the direct treatment of graphene (such as doping transition metal elements and introducing particular type of vacancies). Here we report a way to overcome these difficulties by promoting the reactivity and catalytic activity of graphene via substrate engineering. With thorough first-principles investigations, we demonstrate that when introduce a defect, either a substitutional impurity atom (e.g. Au, Cu, Ag, Zn) or a single vacancy, in the underlying Ru (0001) substrate, the reactivity of the supported graphene can be greatly enhanced, resulting in the chemical adsorption of O 2 molecules on graphene. The origin of the O 2 chemical adsorption is found to be the impurity-or vacancy-induced significant charge transfer from the graphene-Ru (0001) contact region to the 2π* orbital of the O 2 molecule. We then further show that the charge transfer also leads to high catalytic activity of graphene for chemical reaction of CO oxidation. According to our calculations, the catalyzed CO oxidation takes place in Eley-Rideal (ER) mechanism with low reaction barriers (around 0.5 eV), suggesting that the substrate engineering is an effective way to turn the supported graphene into an excellent catalyst that has potential for large-scale industrial applications.

Combating Actions of Green 2D-Materials on Gram Positive and Negative Bacteria and Enveloped Viruses

“…2DMs are the ultrathin nanomaterials with high degree of anisotropy and chemical functionality ( Chimene et al, 2015 ). The era of graphene (Gr) discovery, into single and few layer nanosheets (NSs) has sparked an intense research activity in almost all application areas covering optoelectronics ( Ramanathan et al, 2008 ), catalysis ( Guo et al, 2018 ), energy storage ( Patchkovskii et al, 2005 ; Schedin et al, 2007 ; Dua et al, 2010 ), nano-biosensors ( Kang et al, 2010 ; Gravagnuolo et al, 2015 ; Morales-Narváez et al, 2015 , 2017 ; Cheeveewattanagul et al, 2017 ), polymer composites ( Eda and Chhowalla, 2009 ), vast areas of biomedical studies ( Ghosal and Sarkar, 2018 ) and many more. To unveil the potential of other 2DMs and to supplement the gapless feature of Gr, semiconducting 2D transition metal dichalcogenides (TMDs) such as MoS 2 /WS 2 have been studied nicely because of their tunable band gap and crystal structure engineering.…”

Progress in the Understanding and Applications of the Intrinsic Reactivity of Graphene‐Based Materials

“…[ 15 ] A substrate engineering approach, which introduces a defect, either a substitutional impurity atom (e.g., Au, Cu, Ag, Zn) or a single vacancy, in the underlying Ru (0001) substrate that supports graphene, has also been used to improve the reactivity of graphene for CO reduction. [ 16 ] It is of note that both studies are based on first‐principles calculations and experimental studies are needed to support the conclusions. A recent review for theoretical understanding of various types of graphene‐based catalysis is available.…”

Graphene-Based Heterogeneous Catalysis: Role of Graphene

“…Graphene, a single-atom-thick two-dimensional (2d) material, has attracted enormous interest because of its great potential in electronics originating from its high electrical conductivity and unique electronic structure with zero bandgap [1][2][3][4][5]. However, over the years, this ultra-stable and inert material has gradually found its way as a rising star in catalysis [6][7][8][9][10][11]. In general, a catalyst can be thought of as being composed of two parts, namely, the active site, where the reaction takes place, and the surrounding environment, which plays the role of tuning the electronic structure of the active center to optimize its catalytic activity while maintaining structural integrity during the harsh operating conditions.…”

“…To illustrate the activation of graphene via substrate engineering, Zhang and coworkers turned to graphene on Ru(0001) as the study system [11], as Ru is one of the best substrates for graphene growth, and the system has been clearly elucidated [99,100]. The graphene binds strongly to Ru(0001) and is n-doped, but the significant lattice mismatch of graphene on Ru(0001) gives rise to moiré patterns.…”

“…All of these make graphene stand out from other 2d materials in catalysis applications, because the interactions between graphene and the supported catalyst or the substrate underneath are highly tunable via physical or chemical methods.Noting that pristine graphene is chemically inert, as demonstrated from the small adsorption energies and limited charge transfer of the simulated adsorptions of various clusters and small gaseous molecules on it [13][14][15][16], the biggest issue in graphene-based catalysis is to find effective yet practical ways of activating graphene. This can be achieved via the introduction of defects (by creating vacancies or by doping with foreign atoms [17][18][19][20]) or by either doping the substrate underneath epitaxial graphene [11,21]. In the latter case, graphene can actually function as the catalytic center.…”