Metal nanoparticles have emerged as a new platform for developing highly efficient catalysts and received wide consideration, which has many advantages such as high dispersion and catalytic efficiency. The activity and stability are key factors that influence the practical application of catalysts in industry, and thus to efficiently and facilely tune particle size and stability of catalysts are major concerns and keep as a challenge for the researchers.

Recently, we applied a general atomic layer deposition (ALD) method to synthesize uniformly dispersed Pt nanoparticles with controlled size supported on multi-walled carbon nanotubes (CNTs) with (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe₃) as Pt precursor and ozone as reactant gas. All the ALD-prepared Ptx/CNTs (x represent Pt ALD cycle number, i.e., 10, 20 and 40) catalysts with various cycle numbers show excellent catalytic activities towards hydrolysis reaction of ammonia borane (AB), and especially the Pt/CNTs catalysts produced with 20 ALD cycles (1.8 nm) exhibit the highest hydrogen generation rate among the ALD-prepared catalysts, with a total turnover frequency value as high as 416.5 mol_H2·mol_Pt^-1·min^-1. To improve the durability of Pt/CNTs catalysts, porous TiO₂ overcoats with controlled thickness (13.4 nm, 300-cycle TiO₂) were further deposited on the catalysts as a protective layer to prevent the mobility/leaching of Pt nanoparticles on CNT supports. Our results indicate that the porous TiO₂ overcoat can improve the durability of Pt/CNTs catalysts while preserving their catalytic activities. This can be ascribed to the formation of micro/mesopores due to the densification of an amorphous TiO₂ coating to a crystallized TiO₂ during the calcination process, and it seems that the pores in TiO₂ overcoats are large enough and such thickness of TiO₂ overcoats does not influence the access of AB molecular to the coated Pt nanoparticles as well as the diffusion of targeted products (H₂) because no activity decrease is observed in our experiments.

In summary, the uniformly dispersed Pt nanoparticles deposited on CNTs with narrow size distribution and uniform TiO₂ overcoats on Pt/CNTs were successfully synthesized by ALD, fully demonstrating the advantages of ALD in synthesizing nanocatalysts with high activity and stability. The corresponding results have been published in Catalysis Science & Technology and highlighted as cover paper.