A General Strategy for Ordered Carrier Transport of Quasi‑2D and 3D Perovskite Films for Giant Self‑Powered Photoresponse and Ultrahigh Stability

Organic–inorganic hybrid perovskite materials have been focusing more attention in the field of self-powered photodetectors due to their superb photoelectric properties.However,a universal growth approach is required and challenging to realize vertically oriented growth and grain boundary fusion of 2D and 3D perovskite grains to promote ordered carrier transport,which determines superior photoresponse and high stability.Herein,a general thermal-pressed(TP)strategy is designed to solve the above issues,achieving uniaxial orientation and single-grain penetration along the film thickness direction.It constructs the efficient channel for ordered carrier transport between two electrodes.Combining of the improved crystal quality and lower trap-state density,the quasi-2D and 3D perovskite-based self-powered photodetector devices(with/without hole transport layer)all exhibit giant and stable photoresponse in a wide spectrum range and specific wavelength laser.For the MAPbI_(3)-based self-powered photodetectors,the largest R_(λ) value is as high as 0.57 A W^(−1)at 760 nm,which is larger than most reported results.Meanwhile,under laser illumination(532 nm),the FPEA_(2)MA_(4)Pb_(5)I_(16)-based device exhibits a high responsivity(0.4 A W^(−1)) value,which is one of the best results in 2DRP self-powered photodetectors.In addition,fast response,ultralow detection limit,and markedly improved humidity,optical and heat stabilities are clearly demonstrated for these TP-based devices.

Hydrochloric Acid-Promoted Synthesis of cBN via Hydrothermal Route

Single phase crystalline cubic boron nitride （cBN） with high yield was prepared by hydrothermal route at low temperature, using hydrochloric acid （HCI） as the promoter. The promotion effect of HCI on the synthesis of cBN is briefly discussed.

MoS2-intercalated carbon hetero-layers bonded on graphene as electrode materials for enhanced sodium/potassium ion storage

MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.

Porous-hollow nanorods constructed from alternate intercalation of carbon and MoS2 monolayers for lithium and sodium storage

Weak ion diffusion and electron transport due to limited interlayer spacing and poor electrical conductivity have been identified as critical roadbacks for fast and abundant energy storage of both MoS2-based lithium ion batteries (LIBs) and sodium ion batteries (SIBs). In this work, MoS2 porous-hollow nanorods (MoS2/m-C800) have been designed and synthesized via an annealing-followed chemistry-intercalated strategy to solve the two issues. They are uniformly assembled from ultrathin MoS2 nanosheets, deviated to the rod-axis direction, with expanded interlayer spacing due to alternate intercalation of N-doped carbon monolayers between the adjacent MoS2 monolayers. Electrochemical studies of the MoS2/m-C800 sample, as an anode of LIBs, demonstrate that the superstructure can deliver a reversible discharge capacity of 1,170 mAh·g^-1 after 100 cycles at 0.2 A·g^-1 and maintain a reversible capacity of 951 mAh·g^-1 at 1.25 A·g^-1 after 350 cycles. While for SIBs, the superstructure also delivers a reversible discharge capacity of 350 mAh·g^-1 at 0.5 A-g-1 after 500 cycles and exhibits superior rate capacity of 238 mAh·g^-1 at 15 A·g^-1 .The excellent electrochemical performance is closely related with the hierarchical superstructures, including expanded interlayer spacing, alternate intercalation of carbon monolayers and mesoporous feature, which effectively reduce ion diffusion barrier, shorten ion diffusion paths and improve electrical conductivity.

Preparation and Photocatalytic Properties of g-C_3N_4 /TiO_2 Hybrid Composite

g-C3N4/TiO2 composite were prepared by hydrolysis of Ti（OC4Hn9） 4 and the precursors of g-C3N4 at room temperature and annealing in nitrogen atmosphere.X-ray diffraction results revealed that all the products were anatase structure.The chemical nature of O,N of the g-C 3N4/TiO2 were identified by X-ray photoelectron spectroscopy,presenting N-Ti-O and N-Ti-N doping status of the composite.The g-C3N4 /TiO2 composite showed better photocatalytic activity for the UV and visible-light degradation of Rhodamine B.

Assembly of flower-like VS_(2)/N-doped porous carbon with expanded(001)plane on rGO for superior Na-ion and K-ion storage

VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).

Water-soluble boron carbon oxynitride dots with excellent solid-state fluorescence and ultralong room-temperature phosphorescence

Developing metal-free and long lifetime room-temperature phosphorescence(RTP)materials has received tremendous interest due to their numerous potential applications,of which stable triplet-excited state is the core challenge.Here,boron carbon oxynitride(BCNO)dots,emitting stable blue fluorescence and green RTP,are reported for the first time.The obtained BCNO dots exhibit an unexpected ultralong RTP lifetime of 1.57 s,lasting over 8 s to naked eyes.The effective doping of carbon and oxygen elements in boron nitride(BN)actually provides a small energy gap between singlet and triplet states,facilitating the intersystem crossing(ISC)and populating of triplet excitons.The formation of compact cores via crystallization and effective inter-/intra-dot hydrogen bonds further stabilizes the excited triplet states and reduces quenching of RTP by oxygen at room temperature.Based on the water-soluble feature of BCNO dots,a novel advanced security ink is developed toward anti-counterfeiting tag and confidential information encryption.This study extends BCNO dots to rarely exploited phosphorescence fields and also provides a facile strategy to prepare ultralong lifetime metal-free RTP materials.