Use of Carbon Nitrides as Photoactive Supports in Single‐Atom Heterogeneous Catalysis for Synthetic Purposes

Abstract

In recent years, the field of dual photocatalysis has become an increasingly popular tool for the functionalization of organic substrates under mild operative conditions. Single-atom heterogeneous catalysts (SACs), where the metal atoms are stabilized by means of properly structured photoactive supports, are currently one of the frontiers of this research field. To this end, Carbon Nitrides (CNs) have emerged as ideal two-dimensional semiconducting supports, capable of stabilizing single metal sites (for instance: nickel, iron, among other) through nitrogenrich structures. This Concept highlights the recent advances in the synthesis of carbon nitride-based SACs and their applications in light-driven dual-catalytic processes, also providing forward-looking opportunities within this research area.

Nanostructured Carbon Nitride for Continuous-Flow Trifluoromethylation of (Hetero)arenes

“…Given the excellent performance of mpgC 3 N 4 , we decided to use this photocatalyst to study the effect of band gap modulation on the catalytic activity, through the introduction of isolated metal centers . In the literature, these metal-doped materials have shown enhanced catalytic properties for a number of energy-related reactions and are starting to find applications in organic synthesis. , Metal insertion into the C 3 N 4 framework leads to the creation of a joint electronic structure, which can in turn modify the band gap energy values, correlated also to the optical properties of the material . By fine-tuning this property using metal atoms with different electronic properties, it is possible to precisely engineer the band gap value, which, for mpgC 3 N 4 , is around 2.7 eV (CB = −1.3 eV; VB = 1.4 eV).…”

Carbon nitride based materials: more than just a support for single-atom catalysis

“…It allows better control of loading, although atomic distribution is harder to achieve. 259 For this reason, wet impregnation is not recommended for high-loading targets, as it possibly leads to aggregation as nanoparticles. 259 Indeed, key parameters for the adsorption of single-atoms are the concentration of the precursor and the pH of the aqueous solution.…”

“…259 For this reason, wet impregnation is not recommended for high-loading targets, as it possibly leads to aggregation as nanoparticles. 259 Indeed, key parameters for the adsorption of single-atoms are the concentration of the precursor and the pH of the aqueous solution. 355 Chen et al were one of the first to synthesize CN-based SACs through different methods and exemplified the post-synthetic wet impregnation strategy with Pt, Ir and Pd.…”

“…Between organic/polymeric supports, N-containing materials anchoring SAs have gained attention in the past few years owing to their ability to strong metal coordination and efficient metal-ligand charge transfer. 204,249,250,258,259 N-doped carbon is more regularly employed in SACs than ordinary carbon materials, the latter lacking anchoring points to stabilize highly dispersed metals. Also, the diversity of these compounds provides a large possibility of coordination environments for SAs.…”

Shining Light on Carbon Dots: New Opportunities in Photocatalysis

“…Since the field of dual photocatalysis has grown in interest in recent years, [39] the application of CDs in combination with a metal complex led to mild light‐driven dual‐catalytic processes. An important example in this research area is the work of Pieber and colleagues.…”