The support plays an important role for supported metal catalysts by positioning itself as a macromolecular ligand, which conditions the nature of the active site and contributes indirectly but also sometimes directly to the reactivity. Metal species such as nanoparticles, clusters, or single atoms can be deposited on carbon materials for various catalytic reactions. All the carbon materials used as catalyst support constitute a large family of compounds that can vary both at textural and at structural levels. Today, the recent developments of well-controlled synthesis methodologies, advanced characterization techniques, and modeling tools allow one to correlate the relationships between metal/support/reactant at the molecular level. Based on these considerations, in this Review article, we wish to provide some answers to the question "How and why anchoring metal nanoparticles, clusters, or single atoms on carbon materials for catalysis?". To do this, we will rely on both experimental and theoretical studies. We will first analyze what sites are available on the surface of a carbon support for the anchoring of the active phase. Then, we will describe some important effects in catalysis inherent to the presence of a carbon-type support (metal-support interaction, confinement, spillover, and surface functional group effects). These effects will be commented on by putting into perspective catalytic results obtained in numerous reactions of thermal catalysis, electrocatalysis, or photocatalysis.

A Theory/Experience Description of Support Effects in Carbon-Supported Catalysts.

Research on heterogeneous single-atom catalysts (SACs) has become an emerging frontier in catalysis science because of their advantages in high utilization of noble metals, precisely identified active sites, high selectivity, and tunable activity. Graphene, as a one-atom-thick two-dimensional carbon material with unique structural and electronic properties, has been reported to be a superb support for SACs. Herein, we provide an overview of recent progress in investigations of graphene-based SACs. Among the large number of publications, we will selectively focus on the stability of metal single-atoms (SAs) anchored on different sites of graphene support and the catalytic performances of graphene-based SACs for different chemical reactions, including thermocatalysis and electrocatalysis. We will summarize the fundamental understandings on the electronic structures and their intrinsic connection with catalytic properties of graphene-based SACs, and also provide a brief perspective on the future design of efficient SACs with graphene and graphene-like materials.

Theoretical Understandings of Graphene-based Metal Single-Atom Catalysts: Stability and Catalytic Performance.

Metal nanoparticles supported on two-dimensional graphenes as heterogeneous catalysts

CO oxidation on single Pd atom embedded defect-graphene via a new termolecular Eley-Rideal mechanism

Metal particle size is an important parameter to consider when looking at supported catalyst performances. As for other properties, surface reactivity of metallic nanoparticles is thus highly size‐dependent. The smallest size that can be reached for this type of object is of course the isolated atom deposited on a support. The preparation of single‐atom catalysts (SAC) is not trivial, since to avoid clustering, the mean adsorption energy of the metal on the support should be higher than its cohesive energy. The choice of a support that allows a strongly interacting environment with the metal is therefore a key step in the preparation of such catalysts. The spectrum of carbon (nano)materials is very broad, and their structure as well as their surface chemistry, although sometime complex, can be tuned and exploited for the stabilization of SAC. This Review summarizes in a comprehensive manner experimental and computational studies aiming at: i) preparing SAC on carbon materials, ii) understanding the metal‐support interactions in SAC, and iii) studying how this relates to catalytic performances. The use of SAC follows well the needs dictated by society (energy and environment issues), and many studies have already been published in various fields, such as thermal catalysis, photocatalysis and electrocatalysis.

Single Atom Catalysts on Carbon-Based Materials

The catalytic oxidation of CO on Pd-anchored graphene oxide (Pd-GO) and Pd-embedded vacancy graphene (Pd-VG) is investigated by density functional theory calculations. The results validate both Pd-GO and Pd-VG show good catalytic performance for CO oxidation. Meanwhile, the more positive charge for Pd adatom and the lower reaction energy barrier make Pd-VG system slightly superior than Pd-GO system in catalytic performance. The reaction proceeds via Langmuir–Hinshelwood mechanism with a two-step route (CO + O2 → OOCO → CO2 + O), followed by the Eley–Rideal mechanism (CO + O → CO2). However, the synthesis of Pd-VG is more difficult in experiments compared with the readily available Pd-GO. Hence, graphene oxide may serve as the alternative substrate to deposit Pd nanoparticles.

A comparative study of CO catalytic oxidation on Pd-anchored graphene oxide and Pd-embedded vacancy graphene

Oxidation of Pdn (n = 1–5) clusters on single vacancy graphene: A first-principles study

Effects of N-doping concentration on graphene structures and properties

Electron donor-acceptor (D-A) structure are the most common strategy to develop fluorescent dyes with high quantum yield in solution and the solid state. However, most of the D-A type fluorescent...

Tian-Tian Jia

Papers

A comparative study of CO catalytic oxidation on Pd-anchored graphene oxide and Pd-embedded vacancy graphene

Oxidation of Pdn (n = 1–5) clusters on single vacancy graphene: A first-principles study

Effects of N-doping concentration on graphene structures and properties

Anti-Solvatochromic and Highly Emissive Twisted D-A structure with Intramolecular Hydrogen Bond