Revealing component synergy of Ni‒Fe/black phosphorous composites synthesized by self-designed electrochemical method for enhancing photoelectrocatalytic oxygen evolution reaction

Developing high-activity and low-cost catalysts is the key to eliminate the limitation of sluggish anodic oxygen evolution reaction(OER)during electrocatalytic overall water splitting.Herein,Ni‒Fe/black phosphorous(BP)composites are synthesized using a simple three-electrode system,where exfoliation of bulky BP and synthesis of NiFe composites are simultaneously achieved.Under light illumination,the optimized Ni‒Fe/BP composite exhibits excellent photoelectrocatalytic OER performance(e.g.,the overpotential is 58 mV lower than a commercial RuO_(2) electrocatalyst at a current density of 10 mA·cm^(-2)).The electron transfer on this composite is proved to follow a Ni‒BP‒Fe pathway.The electronic structure of this Ni‒Fe/BP composite is effectively regulated,leading to optimized adsorption strength of the intermediate OH*and improved intrinsic activity for the OER.Together with active sites on the support,this Ni‒Fe/BP composite possesses abundant electrochemical active sites and a bug surface area for the OER.The introduction of light further accelerates the electrocatalytic OER.This work provides a novel and facile method to synthesize high-performance metal/BP composites as well as the approaches to reveal their OER mechanisms.

Holey graphene oxide-templated construction of nano nickel-based metal–organic framework for highly efficient asymmetric supercapacitor

Metal–organic frameworks(MOFs)with redox-active metal sites and controllable crystalline structures make it possible to access the merits of highly-efficient electrode materials in electrochemical energy storage systems.However,most MOFs suffer from low capacitance and poor cycling stability that largely thwart their application.Herein,we present the holey graphene oxide(HGO)template strategy to prepare nano two-dimensional Ni(BDC)with HGO as both template and capping agent(denoted as Ni(BDC)-HGOx,x=10,20,30,and 40 according to the added HGO amount).Structural analyses reveal that HGO can significantly inhibit the Ni(BDC)agglomeration,thus offering a high ion-accessible surface area.Ni(BDC)-HGO30 with well-exposed active sites exhibits a high capacitance of 1,115.6 F·g^(−1) at 1 A·g^(−1) in 6 M KOH aqueous,1.8 times that of bulk Ni(BDC).An asymmetric supercapacitor with Ni(BDC)-HGO30 as a positive electrode and activated carbon as the opposing electrode delivers an energy density of 52.5 W·h·kg^(−1) and a power density up to 18.0 kW·kg−1,with 92.5%capacitance retention after 10,000 cycles.Galvanostatic intermittent titration technique and in situ electrochemical–Raman measurements were exploited to elucidate the electrochemical behavior of Ni(BDC)-HGO30.These results pave the way for the development of rationally tuned MOF materials for enhancing supercapacitor performances.

In situ rapid versatile method for the preparation of zirconium metal-organic framework filters

The development of the rapid preparation of highly stable metal-organic framework(MOF)-based devices provides the possibility of meeting the increasing demands of MOF in industrial applications.However,MOFs experience poor processability and stable high-valence-metal(Ⅳ)-based MOFs favor forming either thermodynamically stable metal hydroxides or oxides during their growth and nucleation,which hinders their practical applications.Herein,we present a versatile deep eutectic solvent(DES)-assisted hot pressing method to in situ rapidly prepare six distinct zirconium-based MOF nanocrystals on fibers(denoted as Zr-MOFilters)within 20 min.A small amount of DES promotes MOF precursor contact and accelerates Zr-MOF growth.Temperature and pressure facilitate the formation of Zr-MOFs onto desired substrates.In situ1H nuclear magnetic resonance spectra and time-dependent Fourier-transform infrared spectra were conducted to elucidate the growth of Zr-MOF nanocrystals.As a proof-of-concept,the abilities of Zr-MOFilters for Cr_(2)O_(7)^(2−) and micro(nano)plastics removal have been demonstrated.This strategy paves the way for the rapid fabrication of highly stable MOF-based devices and brings MOFs a step closer to practical application.

Interface engineering of Co_(3)O_(4)-SmMn_(2)O_(5) nanosheets for efficient oxygen reduction electrocatalysis

Interface engineering is an efficient strategy to modify electronic structure and further improve electrocatalytic activity.Herein,crystalline/amorphous heterostructured Co3O4-SmMn2O5 nanosheets(Co3O4-SMO NSs)have been synthesized by coupling of SMO(electron acceptor)with higher Fermi-level Co3O4(electron donor),via a one-step hydrothermal method followed by calcination.The resulting Co3O4-SMO NSs display higher half-wave potential and specific activity than those of pure SMO or Co3O4.In addition,Co3O4-SMO NSs exhibit superior stability and methanol tolerance.The crystalline/amorphous heterostructure and the electron interaction between SMO and Co3O4 result in interfacial charge transfer.This leads to more active valence states and more oxygen vacancies,optimizing the adsorption energy of O species and expediting electron migration,thus boosting oxygen reduction reaction(ORR)catalytic performance.This study provides a promising strategy to design efficient ORR electrocatalysts by interfacial engineering.

Two SbX_(5)-based isostructural polar 1D hybrid antimony halides with tunable broadband emission,nonlinear optics,and semiconductor properties

Metal halide perovskites based on MX6(M is metal and X is halogen)octahedra have developed into significant materials,extensively used in many fields,such as solid-state lighting,semiconductor,and nonlinear optics.However,the MX_(5)square pyramid-based hybrid metal halides beyond zero-dimensional(0D)polyhedrons and clusters are rarely reported.Herein,we reported two new isostructural hybrid antimony halides,namely(2cepyH)SbCl4(1-Cl)and(2cepyH)SbBr4(2-Br)(2cepy=1-(2-chloroethyl)pyrrolidine),characterized by 1D polar polyanionic chains formed by corner-sharing SbX_(5)tetragonal pyramid units.Upon photoexcitation at 340 nm,1-Cl shows broad,yellow phosphorescence emissions stemming from triplet self-trapped excitons,as proved by its long lifetime(6.85μs)and the temperature dependences of broadband emission.To our knowledge,this should be the first observation on the broadband emissive properties in the 1D hybrid metal halide constructed by MX_(5)tetragonal pyramid units.Moreover,second harmonic generation measurements show that the nonlinear optical properties of 2-Br(∼3.2×KDP)are superior to that of 1-Cl(∼1.8×KDP).Experimental and calculated data indicate that the bandgap of 1-Cl is larger than that of 2-Br and that the polar inorganic moieties determine their band structures.Our work opens up a new way for constructing broadband emission materials with novel polar frameworks.