The surface reconstruction behavior of transition metal phosphides precursors is considered as an important method to prepare efficient oxygen evolution catalysts, but there are still significant challenges in guiding catalyst design at the atomic scale. Here, the CoP nanowire with excellent water splitting performance and stability is used as a catalytic model to study the reconstruction process. Obvious double redox signals and valence evolution behavior of the Co site are observed, corresponding to Co²⁺/Co³⁺ and Co³⁺/Co⁴⁺ caused by auto-oxidation process. Importantly, the in situ Raman spectrum exhibits the vibration signal of Co–OH in the non-Faradaic potential interval for oxygen evolution reaction, which is considered the initial step in reconstruction process. Density functional theory and ab initio molecular dynamics are used to elucidate this process at the atomic scale: First, OH⁻ exhibits a lower adsorption energy barrier and proton desorption energy barrier at the configuration surface, which proposes the formation of a single oxygen (–O) group. Under a higher –O group coverage, the Co–P bond is destroyed along with the PO_x groups. Subsequently, lower P vacancy formation energy confirm that the Ni-CoP configuration can fast transform into a highly active phase. Based on the optimized reconstruction behavior and rate-limiting barrier, the Ni-CoP nanowire exhibit an excellent overpotential of 1.59 V at 10 mA cm⁻² for overall water splitting, which demonstrates low degradation (2.62%) during the 100 mA cm⁻² for 100 h. This work provide systematic insights into the atomic-level reconstruction mechanism of transition metal phosphides, which benefit further design of water splitting catalysts.

SnSe has attracted extensive attention due to its ultralow thermal conductivity and excellent thermoelectric properties. In this work, pressure-induced thermoelectric properties of Pnma SnSe are investigated via first-principles calculations. We uncover distinct energy isosurfaces topology transition of conduction band by applying pressure. The newly created conduction band valley caused by pressure has a distinct anisotropic shape compared to the old one. Inducing pressure can greatly enhance the anisotropy of electronic transport properties of the n-type Pnma SnSe. Furthermore, the lattice thermal conductivity also exhibits anisotropic behavior under pressure due to a special collaged phonon mode. The pressure-induced lattice thermal conductivity along the a-axis shows a slower growth trend than that along the b-axis and c-axis. The optimal ZT value of the n-type Pnma SnSe along the a-axis can reach 1.64 at room temperature. These results would be helpful for designing the Pnma SnSe-based materials for the potential thermoelectric and valleytronic applications.

Engineering the electronic structure of surface active sites at the atomic level can be an efficient way to modulate the reactivity of catalysts. Herein, we report the rational tuning of surface electronic structure of FePS₃ nanosheets (NSs) by anchoring atomically dispersed metal atom. Theoretical calculations predict that the strong electronic coupling effect in single-atom Ni-FePS₃ facilitates electron aggregation from Fe atom to the nearby Ni-S bond and enhances the electron-transfer of Ni and S sites, which balances the oxygen species adsorption capacity, reinforces water adsorption and dissociation process to accelerate corresponding oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The optimal Ni-FePS₃ NSs/C exhibits outstanding electrochemical water-splitting activities, delivering an overpotential of 287 mV at the current density of 10 mA cm⁻² and a Tafel slope of 41.1 mV dec⁻¹ for OER; as well as an overpotential decrease of 219 mV for HER compared with pure FePS₃ NSs/C. The concept of electronic coupling interaction between the substrate and implanted single active species offers an additional method for catalyst design and beyond.