Progress in preparation of high-load atom-dispersed catalysts

[ Instrument Network Instrument Development ] When metal particles are reduced to a certain scale (nanoscale or even atomic dispersion), supported metal catalysts tend to exhibit extremely high catalytic activity due to their high atomic utilization efficiency and unique electronic properties. And specific selectivity. However, as the size of the metal particles decreases, the surface free energy of the metal increases sharply, which easily leads to metal agglomeration. Conventional solutions typically produce atomic-scale dispersed catalysts at the expense of metal loading, which greatly limits the practical application of such catalysts. Recently, Liang Haiwei, a professor at the University of Science and Technology of China, and Dr. Lin Yue, and associate researcher of the Institute of High Energy Physics of the Chinese Academy of Sciences, Chu Shengqi, used high specific surface area sulfur-doped mesoporous carbon (meso_S-C) as a carrier, based on precious metals and sulfur. The principle of strong bond cooperation (according to the soft and hard acid-base theory, precious metals and sulfur belong to soft acid and soft base, respectively, so strong covalent bonds can be formed between them), and a series of high-load atomic-level dispersed precious metal catalysts are prepared. Including Pt, Ir, Rh, Ru, and Pd, wherein the loading of the metal Pt can reach 10 wt%.

In this work, the researchers first synthesized high-sulfur content (14 wt%) using their pre-developed transition metal catalyzed methods of carbonizing organic small molecules (Nature Communications 2015, 6, 7992; Science Advances 2018, 4, eaat0788). And a meso_S-C support with a high specific surface area (>1200 m2 g-1), and a series of atomically dispersed noble metal catalysts were prepared using the support by a conventional impregnation method. Spherical aberration-corrected transmission electron microscopy confirmed that when the Pt and Ir loadings of the metal were less than 10%, no nanoparticles or nanoclusters were found (Fig. 1B and 1D); the X-ray absorption spectrum characterization of synchrotron radiation showed that the metal was mainly made of metal. - Sulfur coordination forms existed, metal-metal coordination was not observed (Figures 1C and 1E), indicating that the metal was present in atomically dispersed form and verified the bonding of the metal to sulfur.

In the electrocatalytic formic acid oxidation reaction, the atomic-dispersed Pt catalyst (10Pt/meso_S-C) has a mass activity of 2.38 A, which is more than 30 times that of the commercial Pt/C catalyst (Fig. 1F); in the catalytic quinoline hydrogenation reaction, The TOF value of the atomic-dispersed Ir catalyst (5Ir/meso_S-C) reached 1292 h-1, which is more than 20 times that of the commercial Ir/C catalyst (Fig. 1G). This work provides a new idea for the universal preparation of high-load atom-level dispersed precious metal catalysts.

The research was funded by the National Natural Science Foundation of China, the Thousand Talents Program Youth Project, the Central University Basic Research Business Fee Special Fund, the Anhui Natural Science Foundation, and the China University of Science and Technology Synchrotron Radiation Joint Fund.