Search

Simultaneously optimizing elementary steps, such as water dissociation, hydroxyl transferring, and hydrogen combination, is crucial yet challenging for achieving efficient hydrogen evolution reaction (HER) in alkaline media. Herein, Ru single atom‐doped WO2 nanoparticles with atomically dispersed Ru–W pair sites (Ru–W/WO2‐800) are developed using a crystalline lattice‐confined strategy, aiming to gain efficient alkaline HER. It is found that Ru–W/WO2‐800 exhibits remarkable HER activity, characterized by a low overpotential (11 mV at 10 mA cm−2), notable mass activity (5863 mA mg−1 Ru at 50 mV), and robust stability (500 h at 250 mA cm−2). The highly efficient activity of Ru–W/WO2‐800 is attributed to the synergistic effect of Ru–W sites through ensemble catalysis. Specifically, the W sites expedite rapid hydroxyl transferring and water dissociation, while the Ru sites accelerate the hydrogen combination process, synergistically facilitating the HER activity. This study opens a promising pathway for tailoring the coordination environment of atomic‐scale catalysts to achieve efficient electro‐catalysis. [ABSTRACT FROM AUTHOR]

Metal phthalocyanines (MPcs) have highly conjugated π electron systems and metal atoms acting as active centers, and so exhibit excellent electrocatalytic performance during the oxygen reduction reaction (ORR). However, these complexes also tend to undergo aggregation and exhibit poor electrical conductivity and minimal durability, all of which hinder their large‐scale industrial applications. In the present study, iron phthalocyanine (FePc) is applied to hollow carbon shells (HCSs) to generate an ORR catalyst containing single Fe atoms(HCS‐O‐FePc). The HCSs have numerous N/O‐based surface functional groups that promote the formation of Fe−O bonds with the FePc held in an axial coordination position. These axial Fe−O bonds disrupt the electron symmetry in the plane of the FePc molecules, which facilitate electron transfer. 1100HCS‐O‐FePc exhibits an onset potential of 0.98 V (vs RHE), a half‐wave potential of 0.91 V (vs RHE), an electron transfer number of 3.90, and durability better than that of a 20 % commercial Pt/C catalyst. Electrochemical impedance spectroscopy demonstrates that the ORR process over this material likely proceeds via a rapid 2+2 electron mechanism. This composite displays excellent oxygen reduction properties and is a promising alternative to Pt‐based ORR catalysts. [ABSTRACT FROM AUTHOR]

The highly efficient electrochemical hydrogen evolution reaction (HER) provides a promising pathway to resolve energy and environment problems. An electrocatalyst was designed with single Mo atoms (Mo-SAs) supported on N-doped carbon having outstanding HER performance. The structure of the catalyst was probed by aberration-corrected scanning transmission electron microscopy (AC-STEM) and X-ray absorption fine structure (XAFS) spectroscopy, indicating the formation of Mo-SAs anchored with one nitrogen atom and two carbon atoms (Mo1N1C2). Importantly, the Mo1N1C2 catalyst displayed much more excellent activity compared with Mo2C and MoN, and better stability than commercial Pt/C. Density functional theory (DFT) calculation revealed that the unique structure of Mo1N1C2 moiety played a crucial effect to improve the HER performance. This work opens up new opportunities for the preparation and application of highly active and stable Mo-based HER catalysts. [ABSTRACT FROM AUTHOR]

• Mo 2 C/CFP-Act is prepared via continuous cathode polarization technique. • Mo 2 C/CFP-Act is an excellent electrocatalyst for the hydrogen evolution reaction. • Mechanism study unveils the Pt single atom intrinsic role in Mo 2 C/CFP catalysts. Dispersing catalytically active metals as single atoms on supports offer an efficient pathway to minimize amount of precious metals. Although platinum (Pt) is highly active for HER, it is highly desirable to find ways to improve the HER performance and also keeping them stable during catalytic reactions while minimizing the Pt loading. Herein, we report a cathode polarization technique to disperse isolated single Pt atoms on β-Mo 2 C as a catalyst for HER. The isolated Pt atoms partially occupy Mo sites in Mo 2 C lattice by forming Pt-Mo shells, which maximize the utilization ratio of platinum noble metals. The single atoms catalyst Mo 2 C/CFP-Act even exhibited 1.9 and 1.1 times higher current density (@ potential of 0.4 V vs. RHE) than that of Pt NPs catalysts (Mo 2 C/CFP-Pt) after mass normalization in both acidic and alkali solution. Furthermore, DFT calculations demonstrate that Mo 2 C/CFP-Act exhibits favorable ΔG H* for the adsorption and desorption of hydrogen. The high HER activity of the Mo 2 C/CFP-Act catalyst is related to the Mo-Pt center located in Mo 2 C matrix, where the electronic structure of the Mo-Pt centers more efficient in donating electron to the σ* antiorbital of the H 3 O+ molecule. This study sheds new light on the HER catalysis mechanism of isolated metal atoms based on fundamental understanding in molecular governing factors. [ABSTRACT FROM AUTHOR]

Tandem Catalysis on dual active sites A highly-efficient electrocatalyst containing dual active sites of Fe-NiOOH and NiC 4 single atoms was synthesized, and a tandem catalysis mechanism of OER on dual active sites was proposed to reveal the high-activity origin of the catalysts. This work provides a new concept of tandem catalysis to develop the electrocatalysts with many elementary steps, like OER and ORR. [Display omitted] • A highly-efficient electrocatalyst containing dual active sites of Fe-NiOOH and NiC 4 single atoms was synthesized. • The dual active site electrocatalyst shows obviously better OER performance than the corresponding single active site one. • A tandem catalysis mechanism was proposed to reveal the synergistic catalysis of two active centers. • This work provides a new concept of tandem catalysis to develop the electrocatalysts with many elementary steps, like OER and ORR The high voltage in oxygen evolution reaction (OER) often causes structural change in electrocatalysts and forms multiple active sites. Therefore, exploring the synergy of various active sites is extremely significant to develop catalysts for OER with multiple elementary steps. Herein, we adopt the physically adsorbed metal ions method to successfully synthesize a highly-efficient electrocatalyst containing the dual active sites of Fe-NiOOH and NiC 4 single atoms (marked as Ni SAs/Fe-NiOOH). The Ni SAs/Fe-NiOOH displays outstanding OER performance with an overpotential of 269 mV to deliver current density of 10 mA/cm2 that shows 55 mV superior to commercial IrO 2 /CB at the same condition. Experiments and density functional theory calculations indicate that the excellent OER activity of Ni SAs/Fe-NiOOH catalyst is attributed to the synergy of dual active sites of NiC 4 SAs and Fe-NiOOH. A tandem catalysis mechanism is also proposed to reveal the synergism of two active centers, which makes the potential-determining step more facile and accordingly decreases the OER overpotential. This work offers a new concept of tandem catalysis to develop the electrocatalysts with many elemental steps, like OER and oxygen reduction reaction catalysts. [ABSTRACT FROM AUTHOR]