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The emerging star of single atomic site (SAS) catalyst has been regarded as the most promising Pt‐substituted electrocatalyst for oxygen reduction reaction (ORR) in anion‐exchange membrane fuel cells (AEMFCs). However, the metal loading in SAS directly affects the whole device performance. Herein, we report a dual nitrogen source coordinated strategy to realize high dense Cu−N4 SAS with a metal loading of 5.61 wt% supported on 3D N‐doped carbon nanotubes/graphene structure wherein simultaneously performs superior ORR activity and stability in alkaline media. When applied in H2/O2 AEMFC, it could reach an open‐circuit voltage of 0.90 V and a peak power density of 324 mW cm−2. Operando synchrotron radiation analyses identify the reconstruction from initial Cu−N4 to Cu−N4/Cu‐nanoclusters (NC) and the subsequent Cu−N3/Cu−NC under working conditions, which gradually regulate the d‐band center of central metal and balance the Gibbs free energy of *OOH and *O intermediates, benefiting to ORR activity. [ABSTRACT FROM AUTHOR]

Hydrodesulfurization (HDS) is an essential process in clean fuel oil production, however, the huge challenge is the synthesis of the catalyst with plentiful active sites. Here, we have shown the design of few-layered, ultrashort Ni-Mo-S slabs dispersed on reduced graphene oxide (Ni-Mo-S/rGO-A) based on anchoring [PMo12O40]3− clusters and Ni2+ on polyethyleneimine (PEI)-modified graphite oxide. Structural characterizations (transmission electron microscopy (TEM), X-ray absorption fine structure (XAFS), etc.) show that Ni-Mo-S slabs with predominant monolayer and partial substitution of edge Mo atoms by isolated Ni atoms have rich accessible edge Ni-Mo-S sites and high sulfurization degree. All virtues endow it with plentiful edge-active sites, and consequently, the enhanced performance for hydrodesulfurization of dibenzothiophene (DBT). The hydrodesulfurization proceeds via a more-favorable direct desulfurization (DDS) route with a reaction rate constant (kHDS) of 48.6 × 10−7 mol·g−1·s−1 over Ni-Mo-S/rGO-A catalyst, which is 4.3 times greater than that over traditional Ni-Mo-S/Al2O3 catalyst and at the forefront of reported catalysts. [ABSTRACT FROM AUTHOR]

Improving the intrinsic catalytic activity of the active phases and mass transfer of the reactants and products are key issues in heterogeneous catalysis. Herein, we construct hollow zeolites with a thin shell of about 10 nm and mesopore structure as supports to load NiMoSX catalysts. On one hand, the nanocages with hollow structures can effectively confine the growth of NiMoSX catalysts, leading to a shorter slab length, higher sulfidation degree, more Ni–Mo–S active sites, and enhanced intrinsic activity. The deep hydrodesulfurization (HDS) activity for dibenzothiophene (DBT) of the NiMoSX/Hol-ZSM-5 catalyst is superior to that of NiMoSX on nanosized ZSM-5 with a reaction rate constant kHDS value of 18.74 × 10−7 mol g−1 s−1. On the other hand, the accessible nanocages and mesopore structure greatly facilitate the mass transfer process and inhibit the formation of carbon deposits, which enhances the HDS stability of NiMoSX/Hol-ZSM-5 to over 80 h. This hollow structure-confined strategy sheds light on the design of novel highly efficient supported catalysts, which we believe could be extended to other heterogeneous catalysis systems. [ABSTRACT FROM AUTHOR]

A proton exchange membrane water electrolyzer (PEMWE) in acidic medium is a hopeful scenario for hydrogen production using renewable energy, but the grand challenge lies in substituting noble‐metal catalysts. Herein, a robust electrocatalyst of V−CoP2 porous nanowires arranged on a carbon cloth is successfully fabricated by incorporating vanadium into the CoP2 lattice. Structural characterizations and theoretical analysis indicate that lattice expansion of CoP2 caused by V incorporation results in the upshift of the d‐band center, which is conducive to hydrogen adsorption for boosting the hydrogen evolution reaction (HER). Besides, V promotes surface reconstruction to generate a thicker Co3O4 layer with an oxygen vacancy that enhances acid‐corrosion resistance and optimizes the adsorption of water and oxygen‐containing species, thus improving activity and stability toward the oxygen evolution reaction (OER). Accordingly, it presents a superior acidic overall water splitting activity (1.47 V@10 mA cm−2) to Pt−C/CC||RuO2/CC (1.59 V@10 mA cm−2), and remarkable stability. This work proposes a new route to design efficient non‐noble metal electrocatalysts for PEMWE. [ABSTRACT FROM AUTHOR]

Development of cost-effective and highly-efficient bifunctional hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalysts is crucial for overall water splitting in practical utilization. Herein, we proposed a novel non-noble metal bifunctional HER/OER electrocatalyst by synergistically coupling a dual-active Co-based heterojunction (Co-CoO) with high conductive and stable two-dimensional Ti3C2-MXene (defined as Co-CoO/Ti3C2-MXene). A series of characterizations and theoretical calculations verify that the synergistic effect of metallic Co with HER activity and CoO with OER performance leads to superb bifunctional catalytic performance, and Ti3C2-MXene can enhance electrical conductivity and prevent the aggregation of the Co-based catalysts, thereby improving both the activity and stability. Co-CoO/Ti3C2-MXene presents low onset potential (ηonset) of 8 mV and Tafel slope of 47 mV·dec−1 for HER (close to that of Pt/C) and ηonset of 196 mV and Tafel slope of 47 mV·dec−1 for OER (superior to that of RuO2). Assembled as an electrolyzer, Co-CoO/Ti3C2-MXene shows a low voltage of 1.55 V at 10 mA·cm−2, high Faradaic efficiency and remarkable stability. It can be driven by a solar cell of ∼ 1.55 V for consecutive production of hydrogen and oxygen gases. [ABSTRACT FROM AUTHOR]

Dual‐metal single‐atom catalysts exhibit superior performance for oxygen reduction reaction (ORR), however, the synergistic catalytic mechanism is not deeply understood. Herein, we report a dual‐metal single‐atom catalyst consisted of Cu−N4 and Zn−N4 on the N‐doped carbon support (Cu/Zn−NC). It exhibits high‐efficiency ORR activity with an Eonset of 0.98 V and an E1/2 of 0.83 V, excellent stability (no degradation after 10 000 cycles), surpassing state‐of‐the‐art Pt/C and great mass of Pt‐free single atom catalysts. Operando XANES demonstrates that the Cu−N4 as active center experiences the change from atomic dispersion to cluster with the cooperation of Zn−N4 during ORR process, and then turns to single atom state again after reaction. DFT calculation further indicates that the adjustment effect of Zn on the d‐orbital electron distribution of Cu could benefit to the stretch and cleavage of O‐O on Cu active center, speeding up the process of rate determining step of OOH*. [ABSTRACT FROM AUTHOR]