Understanding the catalytic mechanism of bimetallic nanocatalysts remains challenging. Here, we adopt an adsorbate mediated thermal reduction approach to yield monodispersed AuPd catalysts with continuous change of the Pd-Au coordination numbers embedded in a mesoporous carbonaceous matrix. The structure of nanoalloys is well-defined, allowing for a direct determination of the structure-property relationship. The results show that the Pd single atom and dimer are the active sites for the base-free oxidation of primary alcohols. Remarkably, the d -orbital charge on the surface of Pd serves as a descriptor to the adsorbate states and hence the catalytic performance. The maximum d -charge gain occurred in a composition with 33–50 at% Pd corresponds to up to 9 times enhancement in the reaction rate compared to the neat Pd. The findings not only open an avenue towards the rational design of catalysts but also enable the identification of key steps involved in the catalytic reactions.

Deep eutectic solvents (DESs) become more attractive in the catalytic field due to their biodegradation, low toxicity, and designability. This study focused on the active sites and influencing factors of 1,3-dimethylurea (1,3-DMU) based DESs in the polyethylene terephthalate (PET) glycolysis process. It is found that the active site of urea derivatives is the amino group, and the basicity and steric hindrance of the amino group affect its catalytic activity. Additionally, the mechanism of PET glycolysis reaction catalyzed by DES was investigated. The outstanding catalytic activity of DES can be attributed to the synergistic effect of acid and base formed between metal salts and 1,3-DMU. Under the optimization conditions, PET (5.0 g), ethylene glycol (20.0 g), and catalyst (n(1,3-DMU)/n(Zn­(OAc)2) 4/1, 0.25 g) at 190 °C for 20 min, the PET conversion is up to 100%, and the yield of bis­(hydroxyalkyl) terephthalate (BHET) is 82%. Furthermore, the kinetic research shows that the glycolysis of PET follows the shrink-core model, and the apparent activity energy is 148.89 kJ/mol.

Carbon monoxide (CO) is notorious for its strong adsorption to poison platinum group metal catalysts in the chemical industry. Here, we conceptually distinguish and quantify the effects of the occupancy and energy of d electrons, emerging as the two vital factors in d-band theory, for CO poisoning of Pt nanocatalysts. The stepwise defunctionalization of carbon support is adopted to fine-tune the 5d electronic structure of supported Pt nanoparticles. Excluding other promotional mechanisms, the increase of Pt 5d band energy strengthens the competitive adsorption of hydrogen against CO for the preferential oxidation of CO, affording the scaling relationship between Pt 5d band energy and CO/H 2 adsorption energy difference. The decrease of Pt 5d band occupancy lowers CO site coverage to promote its association with oxygen for the total oxidation of CO, giving the scaling relationship between Pt 5d occupancy and activation energy. The above insights outline a molecular-level understanding of CO poisoning.