Insight into the synergistic effect of defect and strong interface coupling on ZnIn_(2)S_(4)/CoIn_(2)S_(4)heterostructure for boosting photocatalytic H_(2) evolution

Steering the directional carrier migration across the interface is a central mission for efficient photocatalytic reactions.In this work,an atomic-shared heterointerface is constructed between the defect-rich ZnIn_(2)S_(4)(HVs-ZIS)and CoIn_(2)S_(4)(CIS)via a defect-guided heteroepitaxial growth strategy.The strong interface coupling induces adequate carriers exchanging passageway between HVs-ZIS and CIS,enhancing the internal electric field(IEF)in the ZnIn_(2)S_(4)/CoIn_(2)S_(4)(HVs-ZIS/CIS)heterostructure.The defect structure in HVs-ZIS induces an additional defect level,improving the separation efficiency of photocarriers.Moreover,promoted by the IEF and intimate heterointerface,photogenerated electrons trapped by the defect level can migrate to the valence band of CIS,contributing to massive photogenerated electrons with intense reducibility in HVs-ZIS/CIS.Consequently,the HVs-ZIS/CIS heterostructure performs a boosted H_(2)evolution activity of 33.65 mmol g^(-1)h^(-1).This work highlights the synergistic effects of defect and strong interface coupling in regulating carrier transfer and paves a brave avenue for constructing efficient heterostructure photocatalysts.

Revealing the promising near-room-temperature thermoelectric performance in Ag_(2)Se single crystals

With high carrier mobility and intrinsic low lattice thermal conductivity,Ag_(2)Se compounds have attracted increasing attention for thermoelectric application near room temperature.Due to its phase transition at~406 K and resulting thermal volume expansion,the growth and thermoelectric properties of large-sized Ag_(2)Se single crystals have seldom been reported so far.In this work,the vertical Bridgeman method was used for growing bulk Ag_(2)Se single crystal,with an orientation preference along lowsymmetric(201)plane.The Hall mobility as high as 2000 cm^(2)/(V·s)and weak electron-phonon coupling contributes to a high electronic quality BE of~7.0 in near-room-temperature b-Ag_(2)Se single crystals,which is superior to the high-temperature phase a-Ag_(2)Se.The observed low lattice thermal conductivity of 0.8 W/(m·K)at 300 K is due to the low group speeds and strong anharmonicity.A promising peak zT of 0.66 at 375 K and an average zT of 0.65 at 300-375 K were realized in b-Ag_(2)Se crystals.The low Vickers hardness and good ductile properties were confirmed by experiment and theoretical analysis.This work not only synthesized large-sized and highly-orientated Ag_(2)Se crystals,but also revealed its great potential of thermoelectric performance and mechanical properties for various applications near room temperature.

Band-gap tunable(Ga_(x)In_(1−x))_(2)O_(3)layer grown by magnetron sputtering

Multicomponent oxide(Ga_(x)In_(1−x))_(2)O_(3)films are prepared on(0001)sapphire substrates to realize a tunable band-gap by magnetron sputtering technology followed by thermal annealing.The optical properties and band structure evolution over the whole range of compositions in ternary compounds(Ga_(x)In_(1−x))_(2)O_(3)are investigated in detail.The X-ray diffraction spectra clearly indicate that(Ga_(x)In_(1−x))_(2)O_(3)films with Ga content varying from 0.11 to 0.55 have both cubic and monoclinic structures,and that for films with Ga content higher than 0.74,only the monoclinic structure appears.The transmittance of all films is greater than 86%in the visible range with sharp absorption edges and clear fringes.In addition,a blue shift of ultraviolet absorption edges from 380 to 250 nm is noted with increasing Ga content,indicating increasing band-gap energy from 3.61 to 4.64 eV.The experimental results lay a foundation for the application of transparent conductive compound(Ga_(x)In_(1−x))_(2)O_(3)thin films in photoelectric and photovoltaic industry,especially in display,light-emitting diode,and solar cell applications.