Amorphous and heterojunction materials have been widely used in the field of electrocatalytic hydrogen evolution due to their unique physicochemical properties. However, the current used individual strategy still has limited effects. Hence efficient tailoring tactics with synergistic effect are highly desired. Herein, the authors have realized the deep optimization of catalytic activity by a constructing crystalline–amorphous CoSe2/CoP heterojunction. Benefiting from the strong electronic coupling at the interfaces, the d‐band center of the material moves further down compared to its crystalline–crystalline counterpart, optimizing the valence state and the H adsorption of Co and lowering the kinetic barrier of hydrogen evolution reaction (HER). The heterojunction shows an overpotential of 65 mV to drive a current density of 10 mA cm−2 in the acidic medium. Besides, it also shows competitive properties in both neutral and basic media. This work provides inspiration for optimizing the catalytic activity through combining a crystalline and amorphous heterojunction, which can be implemented for other transition metal compound electrocatalysts.

Crystalline‐Amorphous Interfaces Coupling of CoSe2/CoP with Optimized d‐Band Center and Boosted Electrocatalytic Hydrogen Evolution

Atomically dispersed metal catalysts with well-defined structures have been the research hotspot in heterogeneous catalysis because of their high atomic utilization efficiency, outstanding activity, and selectivity. Dual-atomic-site catalysts (DASCs), as an extension of single-atom catalysts (SACs), have recently drawn surging attention. The DASCs possess higher metal loading, more sophisticated and flexible active sites, offering more chance for achieving better catalytic performance, compared with SACs. In this review, recent advances on how to design new DASCs for enhancing energy catalysis will be highlighted. It will start with the classification of marriage of two kinds of single-atom active sites, homonuclear DASCs and heteronuclear DASCs according to the configuration of active sites. Then, the state-of-the-art characterization techniques for DASCs will be discussed. Different synthetic methods and catalytic applications of the DASCs in various reactions, including oxygen reduction reaction, carbon dioxide reduction reaction, carbon monoxide oxidation reaction, and others will be followed. Finally, the major challenges and perspectives of DASCs will be provided.

Emerging Dual-Atomic-Site Catalysts for Efficient Energy Catalysis

PtSe2 is a typical noble metal dichalcogenide (NMD) that holds promising possibility for next-generation electronics and photonics. However, when applied in hydrogen evolution reaction (HER), it exhibits sluggish kinetics due to the insufficient capability of absorbing active species. Here, we construct PtSe2 /Pt heterointerface to boost the reaction dynamics of PtSe2 , enabled by an in situ electrochemical method. It is found that Se vacancies are induced around the heterointerface, reducing the coordination environment. Correspondingly, the exposed Pt atoms at the very vicinity of Se vacancies are activated, with enhanced overlap with H 1s orbital. The adsorption of H. intermediate is thus strengthened, achieving near thermoneutral free energy change. Consequently, the as-prepared PtSe2 /Pt exhibits extraordinary HER activity even superior to Pt/C, with an overpotential of 42 mV at 10 mA cm-2 and a Tafel slope of 53 mV dec-1 . This work raises attention on NMDs toward HER and provides insights for the rational construction of novel heterointerfaces.

PtSe2 /Pt Heterointerface with Reduced Coordination for Boosted Hydrogen Evolution Reaction.

Optimizing the hydrogen adsorption Gibbs free energy (ΔGH ) of active sites is essential to improve the overpotential of the electrocatalytic hydrogen evolution reaction (HER). We doped graphene-like Co0.85 Se with sulfur and found that the active sites are reversed (from cationic Co sites to anionic S sites), which contributed to an enhancement in electrocatalytic HER performance. The optimal S-doped Co0.85 Se composite has an overpotential of 108 mV (at 10 mA cm-2 ) and a Tafel slope of 59 mV dec-1 , which exceeds other reported Co0.85 Se-based electrocatalysts. The doped S sites have much higher activity than the Co sites, with a hydrogen adsorption Gibbs free energy (ΔGH ) close to zero (0.067 eV), which reduces the reaction barrier for hydrogen production. This work provides inspiration for optimizing the intrinsic HER activity of other related transition metal chalcogenides.

Reversed active sites boost the intrinsic activity of graphene‐like cobalt selenide for hydrogen evolution

Self-Supported Electrocatalysts for Practical Water Electrolysis

Alloying noble metals with non‐noble metals is a promising method to fabricate catalysts, with the advantages of reduced noble metal usage and excellent activity. In this work, electron‐abundant Ir/Rh sites, as highly active centers for the hydrogen evolution reaction (HER), are realized by fabricating Ir1−xRhxSb alloys through the arc‐melting method. The electron transfer from Sb to Ir/Rh makes the latter negatively charged, leading to considerably optimized adsorption for active H species during HER. As a result, the Ir1−xRhxSb alloy exhibits outstanding activity for HER, with an optimized overpotential of 22 mV at 10 mA cm–2 and a Tafel slope of 47.6 mV dec–1. This work provides insights into highly active alloys and sheds light on the utilization of electron‐abundant metal atoms.

Realizing Negatively Charged Metal Atoms through Controllable d‐Electron Transfer in Ternary Ir1−xRhxSb Intermetallic Alloy for Hydrogen Evolution Reaction

Ni-Mo based mixed-phase polyionic compounds nanorod arrays on nickel foam as advanced bifunctional electrocatalysts for water splitting

Degrading organic pollutants using a photocatalyst under visible light is one of the effective ways to solve the increasingly serious environmental pollution problem. In this work, we have loaded a small amount of NiSe2 nanoflakes on the surface of CdS using a simple and low-cost solvothermal synthesis method. The samples were characterized with detailed X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), photocurrent, photoluminescence spectrometer (PL), photocatalytic properties, etc. The results show that a 2 mol% load of NiSe2 increases the rate of degradation of Rhodamine B (RhB) to more than twice the original rate (0.01000 min−1 versus 0.00478 min−1). Meanwhile, the sample has excellent stability. The improved photocatalytic properties can be attributed to the face-to-face contact between the nanoflakes, accelerated separation and transfer of photon-generated carriers. This work provides a suitable co-catalyst that can be used to optimize the performance of other photocatalytic materials.

/pdf/nise2-cds-composite-nanoflakes-photocatalyst-with-enhanced-em8gqu9l7q.pdf

NiSe2/CdS composite nanoflakes photocatalyst with enhanced activity under visible light

Water Splitting In article number 2200855, Wenwu Zhong and co-workers prepare ternary intermetallic Ir1−xRhxSb alloys with negatively charged metal sites, using the arc-melting method, to achieve advanced electrocatalytic activity for the hydrogen evolution reaction. This work provides insights into highly active alloys and sheds light on the utilization of electron-abundant metal atoms. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/aenm.202270108

Realizing Negatively Charged Metal Atoms through Controllable d‐Electron Transfer in Ternary Ir
 1−
 
 x
 
 Rh
 
 x
 
 Sb Intermetallic Alloy for Hydrogen Evolution Reaction (Adv. Energy Mater. 25/2022)

Linghui Yan

Papers

Reversed active sites boost the intrinsic activity of graphene‐like cobalt selenide for hydrogen evolution

Realizing Negatively Charged Metal Atoms through Controllable d‐Electron Transfer in Ternary Ir1−xRhxSb Intermetallic Alloy for Hydrogen Evolution Reaction

Ni-Mo based mixed-phase polyionic compounds nanorod arrays on nickel foam as advanced bifunctional electrocatalysts for water splitting

NiSe2/CdS composite nanoflakes photocatalyst with enhanced activity under visible light

Realizing Negatively Charged Metal Atoms through Controllable d‐Electron Transfer in Ternary Ir 1− x Rh x Sb Intermetallic Alloy for Hydrogen Evolution Reaction (Adv. Energy Mater. 25/2022)