Great enthusiasm in single-atom catalysts (SACs) for the oxygen reduction reaction (ORR) has been aroused by the discovery of M−N X as a promising ORR catalysis center. However, the performance of SACs lags far behind that of stateof-the-art Pt due to the unsatisfactory adsorption−desorption behaviors of the reported catalytic centers. To address this issue, rational manipulation of the active site configuration toward a well-managed energy level and geometric structure is urgently desired, yet still remains a challenge. Herein, we report a novel strategy to accomplish this task through the construction of an Fe−Co dual-atom centered site. A spontaneously absorbed electron-withdrawing OH ligand was proposed to act proactively as an energy level modifier to empower easy intermediate desorption, while the triangular Fe−Co−OH coordination facilitates O−O bond scission. Benefiting from these attributes, the as-constructed FeCoN 5 −OH site enables an ORR onset potential and half-wave potential of up to 1.02 and 0.86 V (vs RHE), respectively, with an intrinsic activity over 20 times higher than the single-atom FeN 4 site. Our finding not only opens up a novel strategy to tailor the electronic structure of an atomic site toward boosted activity but also provides new insights into the fundamental understanding of diatomic sites for ORR electrocatalysis.

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Searching for non-noble metal based electrocatalysts with high efficiency and durability toward hydrogen evolution reaction (HER) is vitally necessary for the upcoming clean and renewable energy systems. Here we report the synthesis of CoP nanoparticles encapsulated in ultrathin nitrogen-doped porous carbon (CoP@NC) through a metal-organic framework (MOF) route. This hybrid exhibits remarkable electrocatalytic activity toward HER in both acidic and alkaline media, with good stability. The experiment and theoretical calculation reveal that the carbon atoms adjacent to N dopants on the shells of CoP@NC are active sites for hydrogen evolution, and CoP and N dopants synergistically optimize the binding free energy of H* on the active sites, which results in a higher electrocatalytic activity than its counterparts without nitrogen doping and/or CoP-encapsulation.

The synthesis of vertical ReS2 nanowalls on 3D graphene foam (V-ReS2 /3DGF) is demonstrated by a chemical vapor deposition route. The vertical nanowall structure leads to an effective exposure of active sites and enhances the lithium interaction with all of the layers. When serving as the anode material for lithium-ion batteries, the V-ReS2 /3DGF composite demonstrates excellent cycling stability at high-current-density.

activities when compared to Pt/C is highly desirable, but still remains challenging.Transition metal phosphides (TMPs) have been investigated as a new class of effective HER catalysts due to their hydrogenase-like catalytic mechanism. [7] It has been reported that the introduction of phosphorus could modify the electronic structure of metal center, resulting in optimized reversible binding of hydrogen, which is considered as the key fact for boosting HER performance. [8] Despite intensive efforts have been made to develop pH-universal TMP-based electrocatalysts with both high-activity and long-term stability, only a few of them could exhibit comparable to, or even better activities than commercial Pt/C in acidic media. Adding insult to injury, Pt-free catalyst with superior catalytic performance to Pt/C under alkaline or/and neutral media has been rarely reported. Very recently, Li's group first reported the successful synthesis of Rh 2 P nanocubes with the average size of about 4.7 nm through a solvothermal method. [9] And the obtained Rh 2 P nanocubes exhibit good HER activities both in 0.5 m H 2 SO 4 and 0.1 m KOH. On the other hand, it is known that catalytic process occurs on the surface of catalysts, thus the size of catalysts is in connection with exposed active site numbers. [10] Experiment results show that nanocatalysts with decreased size often possess higher surface area and more active sites, resulting in enhanced catalytic activity. Consequently, developing ultrasmall TMPs with narrow size distribution may boost HER activity and even superior to the stateof-the-art Pt/C. Inspired by these ideas, in this work, we report the successful colloidal synthesis of monodisperse Rh 2 P nanoparticles (NPs) with an average size of 2.8 nm as well as their superior catalytic performances toward pH-universal HER. As expected, the monodisperse Rh 2 P NPs exhibit higher HER activities than Pt/C over a wide range of pH, with overpotentials of 14, 30, and 38 mV to achieve 10 mA cm −2 in 0.5 m H 2 SO 4 , 1.0 m KOH, and 1.0 m phosphate-buffered saline (PBS), respectively. As far as we know, this is the first example of Pt-free electrocatalyst possessing higher pH-universal HER performance than the state-of-the-art commercial Pt/C. Furthermore, density functional theory (DFT) calculations indicate that the H adsorption strength of Rh 2 P is weakened to nearly zero due to the introduction of P, thereby resulting in the outstanding HER performance.The search for Pt-free electrocatalysts exceeding pH-universal hydrogen evolution reaction (HER) activities when compared to the state-of-the-art commercial Pt/C is highly desirable for the development of renewable energy conversion systems but still remains a huge challenge. Here a colloidal synthesis of monodisperse Rh 2 P nanoparticles with an average size of 2.8 nm and their superior catalytic activities for pH-universal HER are reported. Significantly, the Rh 2 P catalyst displays remarkable HER performance with overpotentials of 14, 30, and 38 mV to achieve 10 mA cm −2 ...