Search

A substrate plays a crucial role in controlled growth and property modulation of two-dimensional (2D) transition-metal dichalcogenides (TMDCs). In this work, we report multiple regulation over grow...

Heterostructure engineering carries prime importance to enhance the catalytic activity of electrocatalysts for water splitting. However, developing nonprecious metal oxides as splendid bifunctional electrocatalysts in alkaline conditions remains a great challenge. Herein, we developed a smart soaking strategy of sulfur/iron ion modification, by which we could activate Co3O4 to spontaneously form heterogeneous structure with excellent hydrogen/oxygen evolution reaction (HER/OER) performance. The nickel foam supported Co3O4 nanoarrays embellished with NiCoSx (NiCoSx@Co3O4 NAs/NF) was easily obtained via sulfur ion modification, which has rich oxygen vacancies and active sites, leading to an outstanding HER performance (η10 = 59 mV, η400 = 264.0 mV). Furthermore, Fe(Ⅱ) ion modified NiCoSx@Co3O4 NAs/NF (FeNiCoS@Co3O4 NAs/NF) achieved superior OER performance (η10 = 226 mV, η400 = 302 mV) than other recently reported cobalt-based catalysts due to the synergistic activity of Ni-Fe-S-Co. More importantly, this work offered a facile and energy-free strategy for developing transition metal oxides as splendid bifunctional catalysts and contributed to the cost and energy savings and mass production for industrial applications as well as the design of advanced functional materials for energy chemistry.

For large-scale implementation of electrochemical hydrogen production, it is essential to develop electrocatalysts that work well at high current densities over a wide pH range. Herein, we use a facile method to synthesize a hierarchical bimetal phosphide (CoP@Ni2P) on nickel foam, which requires very low overpotentials to achieve the benchmark 10 mA cm−2 (e.g., 16 mV in alkaline media). Furthermore, the CoP@Ni2P can deliver a high current density of 500 mA cm−2 at small overpotentials and show no obvious decay after the durability test for over 48 h at all pH levels. The outstanding catalytic performance is attributed to the superaerophobicity of the electrode surface, fast electron transport as well as the increased number of exposed active sites caused by the hierarchical structure and the synergistic effect of the heterostructures. Consequently, this work provides an advanced transition metal-based phosphide for large-scale hydrogen production in all pH ranges.

A unique technique is present to synthesize three dimensional hierarchical vanadium oxides/reduced graphene oxide composites (denoted as 3D VO x /rGO composites) by laser irradiation over the mixture of V 2 O 5 nanobelts and GO nanosheets. Electron microscopy and X-ray photoelectron spectroscopy (XPS) examinations reveal that polydisperse V 2 O 5 /VO 2 heterostructured nanoparticles form strong coupling with rGO. As a result, a specific capacitance of 252 F g −1 is achieved for 3D VO x /rGO composites when used as supercapacitor electrodes, and the capacitance can retain 92% of the initial specific capacitance even after 10000 cycles at a current density of 100 A g −1 . The improvement of supercapacitor performance is achieved by significantly increase on specific surface area of 3D VO x /rGO composites, which favors the easy access of the electrolyte and provides large electroactive surface, and strong V O C bond between VO x nanoparticles and rGO, which benefits the effective charge transfer. We believe that the facile laser irradiation approach represents a major step not only for the simple and efficient fabrication of high performance electrodes but also in the practical application of laser processing to synthesize other functional hierarchical nanocomposites.

Converting CO2 into renewable solar fuel using photocatalysts is one of the most ideal solutions for environmental challenges and energy crises. Here, the solid-solid Z-scheme Zn0.5Cd0.5S/Au@g-C3N4 (ZCS/Au@CN) heterojunction showed improved photocatalytic reduction of CO2 due to the enhanced visible light consumption, fast dissolution of photogenerated electron-hole pairs, quick interfacial transfer process of electrons, and enlarged surface area. Under visible-light irradiation, methanol (CH3OH) was produced at a rate of 1.31 μmol h−1 g−1 over ZCS/Au@CN, roughly 43.6 and 32.7 folds higher than those observed over pure ZCS and CN samples. The analytical characterization results verified the role of AuNPs as an electron mediator, which improved the rapid extraction of photoinduced electrons and enhanced the reduction ability of CO2. This work not only demonstrates a facile photodeposition assisted hydrothermal method for fabrication of ZnxCd1-xS/Au@C3N4 heterojunction composite photocatalysts but also demonstrates the possibility of utilizing ternary composites for enhanced photocatalytic reduction of CO2.

Transition metal chalcogenides with abundant active edge sites and suitable structures for large-scale water splitting in alkaline hydrogen evolution reaction (HER) are challenging but promising. Herein, hierarchical heterostructured nickel foam–supported Co3S4 nanorod arrays embellished with edge-exposed MoS2 nanoflakes (Edge-MoS2/Co3S4@NFs) as an effective HER catalyst are designed. There into, porous nickel foam and moderately distributed nanorod arrays of Edge-MoS2/Co3S4@NFs provide multiscale pathways for efficient charge and mass transport and significantly enlarge the surfaces for the deposition of MoS2 flakes. The superhydrophilic/aerophobic surface improves the electrolyte transport and facilitates the detachment of hydrogen bubbles from the surface of the catalyst. The MoS2 flakes anchored on nanorods are well dispersed with plentiful active sites exposed which enhance the intrinsic activity of active sites owing to the adequate intersection of charge and mass. In addition, there is a synergetic effect of bimetal sulfides, evidenced by increasing the turnover frequency. Therefore, the Edge-MoS2/Co3S4@NF affords a low overpotential (η10 = 90.3 mV and η1000 = 502.0 mV) and small Tafel slope (61.69 mV dec−1). This study provides a facile strategy to develop electrocatalysts through the synergy of enhanced thermodynamic and kinetic processes, shedding lights on the advanced design of functional materials for energy chemistry.

MXenes and doped carbon nanotubes (CNTs) have entered into research arenas for high-rate energy storage and conversion. Herein, a method of postsynthesis of MXenes in boron, nitrogen codoped CNTs (BNCNTs) is reported with their electrocatalytical hydrogen evolution performance. The encapsulation of hexagonal molybdenum nitrate nanoparticles (h-MoN NPs) into BNCNTs protects h-MoN NPs from agglomeration and poisoning in the complex environment. In principle, the synergism of B and N dopants on the doped CNTs and confined h-MoN NPs produces extremely active sites for electrochemical hydrogen evolution. Density functional theory calculations reveal that the active sites for hydrogen evolution originate from the synergistic effect of h-MoN(001)/CN (graphitic N doping) and h-MoN(001)/BNC. The h-MoN@BNCNT electrocatalyst exhibits a small overpotential of 78 mV at 10 mA cm and Tafel slope of 46 mV per decade, which are dramatically improved over all reported MoN-based materials and doped CNTs. Additionally, it also exhibits outstanding electrochemical stability in environments with various pH values and seawater media from South China Sea.