The bright future of single atom catalysis

Single-atom catalysis (SAC) is an exciting term that has been widely used lately. It is a recently established field that aims to bring the advantages of both heterogeneous and homogeneous catalysis together. Exciting, but difficult to realize. To develop this field, many low–cost and high–cost devices have been build to synthesize and characterize such materials. In this work we show the advantages of using atom isolated catalysts despite its tough synthesis procedures.
We first demonstrated a design and kinetic testing strategy for synthesizing isolated pairs of active sites. We show the unique performance and explain solvent based kinetics related to isolated sites as a means of identifying the pair versus the isolated site. We explain that the use of such model reactions is only possible with low-background reactions of the support because of (i) higher signal to noise ration, (ii) chemical isolation instead of only physical isolation, (iii) suppressing metal-support interaction for catalysis.
Moreover, proving that isolated atoms outperform their nanoparticle counterparts is of vital importance and discussed as well. We exemplify this in a photocatalytic model reaction and show the performance of these materials and rationalize their inefficiencies. The model reaction is of further interest to sustainable hydrocarbon decomposition. We in addition show that organic deposition decreases the bandgap of TiO₂ which was used to improve the energy efficiency of oxidation.
We then mention the use of a super dissolution model of Rh/Al₂O₃ combinations to do catalysis. In this material, strong rhodium-aluminate bonds are formed which can be broken at high reducing environment under high temperatures. We show that in the case of Rh/Al₂O₃, the deactivation caused by sintering can temporarily be prevented using the dissolution/exsolution of metal atoms into/from the support. We design and synthesize a series of single-atom catalysts and study the impact of exsolution in the dry reforming of methane at 700–900 °C. The catalysts’ performance increases with increasing reaction time, as the rhodium atoms migrate from the subsurface to the surface.