Search

The oxygen evolution reaction (OER), a crucial semireaction in water electrolysis and rechargeable metal-air batteries, is vital for carbon neutrality. Hindered by a slow proton-coupled electron transfer, an efficient catalyst activating the formation of an O-H bond is essential. Here, we proposed a straightforward one-step hydrothermal procedure for fabricating PO 4 3- -modified NiFe layered double-hydroxide (NiFe LDH) catalysts and investigated the role of PO 4 3- anions in enhancing OER. Phosphate amounts can efficiently regulate LDH morphology, crystallinity, composition, and electronic configuration. The optimized sample showed a low overpotential of 267 mV at 10 mA cm -2 . Density functional theory calculations revealed that intercalated and surface-adsorbed PO 4 3- anions in NiFe LDH reduced the Gibbs free energy in the rate-determining step of *OOH formation, balancing oxygen-containing intermediate adsorption/dissociation and promoting the OER. Intercalated phosphate ions accelerated precatalyst dehydrogenation kinetics, leading to a rapid reconstruction into active NiFe oxyhydroxide species. Surface-adsorbed PO 4 3- interacted favorably with adsorbed *OOH on the active Ni sites, stabilizing *OOH. Overall, the synergistic effects of intercalated and surface-adsorbed PO 4 3- anions significantly contributed to enhanced OER activity. Achieving optimal catalytic activity requires a delicate equilibrium between thermodynamic and kinetic factors by meticulously regulating the quantity of introduced PO 4 3- ions. This endeavor will facilitate a deeper comprehension of the influence of anions in electrocatalysis for OER.

Molybdenum disulfide (MoS 2 ) has attracted much attention as a promising alternative to Pt-based catalysts for highly efficient hydrogen generation. However, it suffers sluggish kinetics for driving the hydrogen evolution reaction (HER) process because of inert basal planes, especially in alkaline solution. Here, we show a combination of heteroatom doping and phase transformation strategies to engineer the in-plane structure of MoS 2 , that trigger their catalytic activities. Systematic characterizations are performed with advanced aberration-corrected microscopy and X-ray techniques, indicating that an as-designed MoS 2 catalyst has a distorted zigzag-chain superlattice in metallic phase, while its in-plane structure was engineered via the incorporation of cobalt and oxygen species. The optimal Co, O dual-doped metallic phase molybdenum disulfide (1T-MoS 2 ) electrocatalyst shows a significantly enhanced HER activity with a low overpotential of 113 mV at 10 mA cm -2 and corresponding small Tafel slope of 50 mV dec -1 , accompanied by the robust stability in alkaline media. The calculated turnover frequency is higher than 6.65 H 2 s -1 at an overpotential of 200 mV. More in-depth insights from the first-principle calculations illustrate that the water dissociation as a rate-determining step was largely accelerated by the in-plane Co-O-Mo species and fast electron transfer of the catalyst. Benefiting from ingenious design and fine identifications, this work provides a fundamental understanding of the relationships among heteroatom doping, phase transformation, and performance for MoS 2 -based catalysts.

Rationally designing cheap and efficient electrocatalysts at the atomic level is highly desirable for the hydrogen evolution reaction (HER). Here, we demonstrate a metallic MoS 2 electrocatalyst decorated with platinum single atoms. When combined with electron microscopy observations, our synchrotron X-ray characterizations and theoretical calculations clearly reveal that the doped Pt atoms bond to S atoms on the surface of MoS 2 . Notably, these Pt single atoms serve as critical active centers for the HER through capturing H + from the solution. The optimized Pt-MoS 2 catalysts achieve significantly enhanced HER performance due to the single-atom coordination effect. This finding is expected to facilitate further realization of hybridized catalysts through the monatomic riveting strategy.

Atomic intercalation of different agents into 2D layered materials can engineer the intrinsic structure on the atomic scale and thus tune the physical and chemical properties for specific applications. Here we successfully introduce tin (Sn) atoms into the interlayer of α-MoO 3 nanobelts forming a new MoO 3 -Sn intercalation with ultrastable structure. Combining with theoretical calculations, our synchrotron radiation-based characterizations and electron microscope observations clearly reveal that the intercalated Sn atoms could bond with five O atoms, forming a pentahedral structure. Subsequently, the Sn-O bonds induce a less distorted [MoO 6 ] octahedral structure, resulting in a unique structure that is distinct with pristine α-MoO 3 or any other molybdenum oxides. Employed as anode for lithium-ion battery, the as-prepared MoO 3 -Sn nanobelts display a much higher capacity of 520 mAhg -1 at 500 mAg -1 than α-MoO 3 nanobelts (291 mAhg -1 ), with a Coulombic efficiency of 99.5%. Moreover, owing to the strong intercalation from Sn ions, the MoO 3 -Sn nanobelts pose superior cyclability, durability, and reliability.