Regulating the Tip Effect on Single-Atom and Cluster Catalysts: Forming Reversible Oxygen Species with High Efficiency in Chlorine Evolution Reaction.

Chlorine evolution reaction has been applied in the production since a century ago. After times of evolution, it has been widely realized by the electrocatalytic process on anode nowadays. However, the anode applied in production contains a large amount of precious metal, increasing the cost. It is thus an opportunity to apply sub-nano catalysts in this field. By regulating the tip effect (TE) of the catalyst, it was discovered that the oxidized sub-nano iridium clusters supported by titanium carbide exhibit much higher efficiency than the single-atom one, which demonstrates the significance of modifying the electronic interaction. Moreover, it exhibits a ≈20 % decrease of the electricity, ≈98 % selectivity towards chlorine evolution reaction, and high durability of over 350 h. Therefore, this cluster catalyst performs great potential in applying in the practical production and the comprehension of the tip effect on different types of catalysts is also pushed to a higher level.

Chiral Primary Amine/Ketone Cooperative Catalysis for Asymmetric α-Hydroxylation with Hydrogen Peroxide.

Carbonyls and amines are yin and yang in organocatalysis as they mutually activate and transform each other. These intrinsically reacting partners tend to condense with each other, thus depleting their individual activity when used together as cocatalysts. Though widely established in many prominent catalytic strategies, aminocatalysis and carbonyl catalysis do not coexist well, and, as such, a cooperative amine/carbonyl dual catalysis remains essentially unknown. Here we report a cooperative primary amine and ketone dual catalytic approach for the asymmetric α-hydroxylation of ß-ketocarbonyls with H2O2. Besides participating in the typical enamine catalytic cycle, the chiral primary amine catalyst was found to work cooperatively with a ketone catalyst to activate H2O2 via an oxaziridine intermediate derived from an in-situ-generated ketimine. Ultimately, this enamine-oxaziridine coupling facilitated the highly controlled α-hydroxylation of several ß-ketocarbonyls in excellent yield and enantioselectivity. Notably, late-stage hydroxylation for peptidyl amide or chiral esters can also be achieved with high stereoselectivity. In addition to its operational simplicity and mild conditions, this cooperative amine/ketone catalytic approach also provides a new strategy for the catalytic activation of H2O2 and expands the domain of typical amine and carbonyl catalysis to include this challenging transformation.

The Electronic Metal-Support Interaction Directing the Design of Single Atomic Site Catalysts: Achieving High Efficiency Towards Hydrogen Evolution.

It is still of great difficulty to develop the non-platinum catalyst with high catalytic efficiency towards hydrogen evolution reaction via the strategies till now. Therefore, it is necessary to develop the new methods of catalyst designing. Here, we put forward the catalyst designed by the electronic metal-support interaction (EMSI), which is demonstrated to be a reliable strategy to find out the high-efficiency catalyst. We carried out the density functional theory calculation first to design the proper EMSI of the catalyst. We applied the model of M1-M2-X (X=C, N, O) during the calculation. Among the catalysts we chose, the EMSI of Rh1TiC, with the active sites of Rh1-Ti2C2, is found to be the most proper one for HER. The electrochemical experiment further demonstrated the feasibility of the EMSI strategy. The single atomic site catalyst of Rh1-TiC exhibits higher catalytic efficiency than that of state-of-art Pt/C. It achieves a small overpotential of 22 mV and 86 mV at the at the current density of 10 mA cm-2 and 100 mA cm-2 in acid media, with a Tafel slope of 25 mV dec-1 and a mass activity of 54403.9 mA cm-2 mgRh -1 (vs. 192.2 mA cm-2 mgPt -1 of Pt/C). Besides, it also shows appealing advantage in energy saving compared with Pt/C (≈20 % electricity consuming decrease at 2 kA m-2 ) Therefore, we believe that the strategy of regulating EMSI can act as a possible way for achieving the high catalytic efficiency on the next step of SACs.