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Developing low‐cost and high‐efficient bifunctional catalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is greatly significant for water electrolysis. Here, Ni3N‐CeO2/NF heterostructure is synthesized on the nickel foam, and it exhibits excellent HER and OER performance. As a result, the water electrolyzer based on Ni3N‐CeO2/NF bifunctional catalyst only needs 1.515 V@10 mA cm−2, significantly better than that of Pt/C||IrO2 catalysts. In situ characterizations unveil that CeO2 plays completely different roles in HER and OER processes. In situ infrared spectroscopy and density functional theory calculations indicate that the introduction of CeO2 can optimizes the structure of interface water, and the synergistic effect of Ni3N and CeO2 improve the HER activity significantly, while the in situ Raman spectra reveal that CeO2 accelerates the reconstruction of OV (oxygen vacancy)‐rich NiOOH for boosting OER. This study clearly unlocks the different catalytic mechanisms of CeO2 for boosting the HER and OER activity of Ni3N for water splitting, which provides the useful guidance for designing the high‐performance bifunctional catalysts for water splitting. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen evolution reaction (HER) is one of the green and effective method to produce clean hydrogen energy. However, the development of non-Pt HER catalysts with excellent catalytic activity and long-term stability still remains a great challenge. Herein, a vertically aligned core-shell structure material with hollow polypyrrole (PPy) nanowire as a core and Ru-doped MoS 2 (Ru–MoS 2) nanosheets as a shell is firstly reported as a highly efficient and ultra-stable catalyst for HER in alkaline solutions. Results indicate that Ru–MoS 2 @PPy catalyst demands a low overpotential of 37 mV at 10 mA cm−2. In addition, the overpotential at 100 mA cm−2 is 157 mV and it is almost unchanged after 40,000 cyclic voltammetry cycles. The existence of PPy core not only ensures the vertical growth of MoS 2 nanosheets to expose more edge sites, but also promotes the rapid transfer of electrons, contributing to the improvement of catalytic activity. More importantly, the strong interface interaction between MoS 2 and PPy prevents the collapse of the vertical structure of MoS 2 sheets in the electrocatalytic process and greatly enhances the stability of catalysts, which offers an effective strategy to design and synthesize the HER catalysts with superior catalytic stability. • The in-situ growth method was used to prepare the 3D core-shell MoS 2 @PPy. • In-situ growth enhances the interface interaction between MoS 2 and PPy. • Ru–MoS 2 @PPy exhibits promising HER activity and stability. [ABSTRACT FROM AUTHOR]

Abstract: Though many chiral amines such as l-proline and its derivatives have proven to be versatile catalysts in many reactions, l-prolinol was seldom used as organocatalyst for reactions. Herein, we report the first l-prolinol catalyzed asymmetric Michael addition of cyclohexanone to nitroolefins in the presence of benzoic acid to afford Michael adducts with high diastereoselectivities (87:13–>99:1) and enantioselectivities (82–96%). [Copyright &y& Elsevier]

Ru monolayer islands-doped MoS 2 catalysts were prepared by the high-gravity technology, and the catalyst exhibits ultralow overpotential of 17 mV at 10 mA cm−2 in alkaline medium, which is attributed to its high-density active sites. [Display omitted] • Ru monolayer islands-doped MoS 2 catalysts (MIs-MoS 2) have been prepared by the high-gravity technology. • MIs-MoS 2 possesses high-density active sites for boosting the HER activity. • MIs-MoS 2 exhibits ultralow overpotential of 17 mV at 10 mA cm−2 in alkaline medium. • DFT calculations reveal that Ru monolayer doping can optimize the electronic structure to boost HER performance. Developing highly-efficient hydrogen evolution reaction (HER) catalysts is significantly important for hydrogen generation by water splitting. In this work, Ru monolayer islands (MIs)-doped MoS 2 catalysts are synthesized controllably by high-gravity technology. Ru MIs are successfully anchored on the MoS 2 nanosheets via the coordination of Ru and S species in the MoS 2 matrix to form monolayer island structure, which not only provides high-density active centers for boosting the HER activity, but also exhibits the maximum atomic utilization. The prepared Ru MIs-doped MoS 2 catalysts exhibit a remarkably low overpotential of 17 mV at the current density of 10 mA cm−2 (η 10) in alkaline conditions. Density functional theory (DFT) results reveal that multi-Ru monolayer doping can efficiently tailor the electronic structure and improve the adsorption of hydrogen on MoS 2 , and thereby boost the catalytic activity of HER. This work provides a Ru MIs doping approach to enhance the density of active sites of electrocatalysts, which would overcome the bottleneck of low active site density of single-atom catalysts to design high-efficient electrocatalysts with maximum atomic utilization. [ABSTRACT FROM AUTHOR]