In-Situ Growth of NiFe₂O₄/2D MoS₂ p‑n Heterojunction Immobilizing Palladium Nanoparticles for Enhanced Visible-Light Photocatalytic Activities

Solar energy is considered as a green and abundant energy for catalytic reactions. In this work, a magnetically recoverable NiFe₂O₄/2D MoS₂–Pd nanocomposite is successfully synthesized via a simple one-pot hydrothermal method. The intimate interfacial contact between NiFe₂O₄ nanocubes and corrugated MoS₂ nanosheets forms the NiFe₂O₄/2D MoS₂ p-n heterojunction, while plasmonic Pd nanoparticles are uniformly immobilized on the surface of it. Dye degradation and Suzuki-Miyaura coupling reaction are employed to evaluate the photocatalytic activity of the NiFe₂O₄/2D MoS₂–Pd nanocomposite. Significantly, both dye degradation and Suzuki-Miyaura coupling reaction can be efficiently performed in a short time under mild conditions. In comparison, the physically mixed NiFe₂O₄+2D MoS₂ heterojunction immobilizing palladium nanoparticles shows poor photocatalytic activity. Photocatalytic results demonstrate that the in situ formation of NiFe₂O₄/2D MoS₂ p-n heterojunction greatly improves the visible-light absorption and facilitates the transferring of photogenerated electrons and holes. Moreover, Pd nanoparticles as the electron reservoirs can further suppress the electron–hole recombination and enhance the photocatalytic activity. The construction of semiconductive p-n heterojunction to immobilize metal nanocatalysts will be an inspiration for other useful photocatalytic applications

Dual-Functional Starfish-like P‑Doped Co–Ni–S Nanosheets Supported on Nickel Foams with Enhanced Electrochemical Performance and Excellent Stability for Overall Water Splitting

Dual-functional electrocatalysts have recently been reported to improve the conversion and storage of energy generated from overall water splitting in alkaline electrolytes. Herein, for the first time, a shape-controlled synthesis of starfish-like Co–Ni–S nanosheets on three-dimensional (3D) hierarchically porous nickel foams (Co–Ni–S/NF) via a one-step hydrothermal method was developed. The influence of reaction time on the nanosheet structure and properties was intensively studied. After 11 h reaction, the Co–Ni–S/NF-11 sample displays the most regular structure of nanosheets and the most outstanding electrochemical properties. As to water splitting, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) required overpotentials of 284.3 and 296 mV, respectively, to provide a current density of 100 mA cm^–2. The marvelous electrochemical performance can be attributed to the conductive networks of 3D layered porous nickel skeletons that are highly interconnected, which provided a large specific area and highly active sites. To further enhance the electrochemical performances of the electrocatalyst, the influence of the doping of the P element was also studied. The results proved that the P-doped Co–Ni–S/NF maintains the starfish structure and demonstrates outstanding properties, providing a current density of 100 mA cm^–2 with only 187.4 and 292.2 mV overpotentials for HER and OER, respectively. It exhibited far more excellent properties than reported dual-functional electrocatalysts. Additionally, when used as an overall water-splitting catalyst, P–Co–Ni–S/NF can provide a 10 mA cm^–2 current density at a given cell voltage of 1.60 V in 1 M KOH, which is competitive to the best-known electrocatalysts, with high long-term stability

Controlled Electrodeposition Synthesis of Co–Ni–P Film as a Flexible and Inexpensive Electrode for Efficient Overall Water Splitting

Synthesis of highly efficient and robust catalysts with earth-abundant resources for overall water splitting is essential for large-scale energy conversion processes. Herein, a series of highly active and inexpensive Co–Ni–P films were fabricated by a one-step constant current density electrodeposition method. These films were demonstrated to be efficient bifunctional catalysts for both H₂ and O₂ evolution reactions (HER and OER), while deposition time was deemed to be the crucial factor governing electrochemical performance. At the optimal deposition time, the obtained Co–Ni–P-2 catalyst performed remarkably for both HER and OER in alkaline media. In particular, it requires −103 mV overpotential for HER and 340 mV for OER to achieve the current density of 10 mA cm^–2, with corresponding Tafel slopes of 33 and 67 mV dec^–1. Moreover, it outperforms the Pt/C//RuO₂ catalyst and only needs −160 mV (430 mV) overpotential for HER (OER) to achieve 200 mA cm^–2 current density. Co–Ni–P electrodes were also conducted for the proof-of-concept exercise, which were proved to be flexible, stable, and efficient, further opening a new avenue for rapid synthesis of efficient, flexible catalysts for renewable energy resources

Controlled Electrodeposition Synthesis of Co–Ni–P Film as a Flexible and Inexpensive Electrode for Efficient Overall Water Splitting

Synthesis of highly efficient and robust catalysts with earth-abundant resources for overall water splitting is essential for large-scale energy conversion processes. Herein, a series of highly active and inexpensive Co–Ni–P films were fabricated by a one-step constant current density electrodeposition method. These films were demonstrated to be efficient bifunctional catalysts for both H₂ and O₂ evolution reactions (HER and OER), while deposition time was deemed to be the crucial factor governing electrochemical performance. At the optimal deposition time, the obtained Co–Ni–P-2 catalyst performed remarkably for both HER and OER in alkaline media. In particular, it requires −103 mV overpotential for HER and 340 mV for OER to achieve the current density of 10 mA cm^–2, with corresponding Tafel slopes of 33 and 67 mV dec^–1. Moreover, it outperforms the Pt/C//RuO₂ catalyst and only needs −160 mV (430 mV) overpotential for HER (OER) to achieve 200 mA cm^–2 current density. Co–Ni–P electrodes were also conducted for the proof-of-concept exercise, which were proved to be flexible, stable, and efficient, further opening a new avenue for rapid synthesis of efficient, flexible catalysts for renewable energy resources

Liquid Phase Exfoliation of Two-Dimensional Materials by Directly Probing and Matching Surface Tension Components

Exfoliation of two-dimensional (2D) materials into mono- or few layers is of significance for both fundamental studies and potential applications. In this report, for the first time surface tension components were directly probed and matched to predict solvents with effective liquid phase exfoliation (LPE) capability for 2D materials such as graphene, h-BN, WS₂, MoS₂, MoSe₂, Bi₂Se₃, TaS₂, and SnS₂. Exfoliation efficiency is enhanced when the ratios of the surface tension components of the applied solvent is close to that of the 2D material in question. We enlarged the library of low-toxic and common solvents for LPE. Our study provides distinctive insight into LPE and has pioneered a rational strategy for LPE of 2D materials with high yield