溶液酸度和反应温度对CaMoO_4薄膜电化学制备的影响

本工作研究了恒电流电化学技术制备CaMoO4薄膜工艺中,溶液酸度和反应温度对薄膜形成的影响。结果表明,酸度会影响薄膜的生长时间和光致发光特性,在较低酸度沉积薄膜时,容易造成薄膜的团簇生长和不确定相的形成;适当升高反应温度会加快晶粒的生长、提高薄膜的纯度、增加薄膜发射光谱的相对强度。在CaMoO4薄膜电化学制备工艺中,溶液pH值控制在12.0附近和反应温度控制在60℃的左右比较好。

从人生3个片段透视侯德榜先生的爱国情怀

2011年，是联合国确定的“国际化学年”，也是中国化学工业史杰出科学家侯德榜先生诞辰121周年。通过节选侯德榜先生一生几个关键节点，重现侯德榜先生爱国爱民情怀的演变和升华，一则缅怀侯德榜先生，二来期望能让年轻一代读后有所感悟。

Characterization and photoelectrochemical performance of Zn-doped TiO_2 films by sol-gel method

Zn-doped TiO2 (Zn?TiO2) thin films were prepared by the sol?gel method on titanium substrates with heat treatment at different temperatures. The effects of heat treatment temperatures and Zn doping on the structure, photocathodic protection and photoelectrochemical properties of TiO2 thin films were investigated. It is indicated that the photoelectrical performance of the Zn?TiO2 films is enhanced with the addition of Zn element compared with the pure-TiO2 film and the largest decline by 897 mV in the electrode potential is achieved under 300 °C heat treatment. SEM?EDS analyses show that Zn element is unevenly distributed in Zn?TiO2 films; XRD patterns reveal that the grain size of Zn?TiO2 is smaller than that of pure-TiO2; FTIR results indicate that Zn - O bond forms on Zn?TiO2 surface. Ultraviolet visible absorption spectra prove that Zn?TiO2 shifts to visible light region.Mott?Shottky curves show that the flat-band potential of Zn?TiO2 is more negative and charge carrier density is bigger than that ofpure-TiO2, implying that under the synergy of the width of the space-charge layer, carrier density and flat-band potential, Zn?TiO2 with 300 °C heat treatment displays the best photocathodic protection performance.

GW/BSE Nonadiabatic Dynamics Simulations on Excited-State Relaxation Processes of Zinc Phthalocyanine-Fullerene Dyads:Roles of Bridging Chemical Bonds

In this work,we employ electronic structure calculations and nonadiabatic dynamics simulations based on many-body Green function and BetheSalpeter equation(GW/BSE)methods to study excited-state properties of a zinc phthalocyanine-fullerene(ZnPcC_(60))dyad with 6-6 and 5-6 configurations.In the former,the initially populated locally excited(LE)state of ZnPc is the lowest S1 state and thus,its subsequent charge separation is relatively slow.In contrast,in the latter,the S1 state is the LE state of C_(60)while the LE state of ZnPc is much higher in energy.There also exist several charge-transfer(CT)states between the LE states of ZnPc and C_(60).Thus,one can see apparent charge separation dynamics during excited-state relaxation dynamics from the LE state of ZnPc to that of C_(60).These points are verified in dynamics simulations.In the first 200 fs,there is a rapid excitation energy transfer from ZnPc to C_(60),followed by an ultrafast charge separation to form a CT intermediate state.This process is mainly driven by hole transfer from C_(60)to ZnPc.The present work demonstrates that different bonding patterns(i.e.5-6 and 6-6)of the C−N linker can be used to tune excited-state properties and thereto optoelectronic properties of covalently bonded ZnPc-C_(60)dyads.Methodologically,it is proven that combined GW/BSE nonadiabatic dynamics method is a practical and reliable tool for exploring photoinduced dynamics of nonperiodic dyads,organometallic molecules,quantum dots,nanoclusters,etc.

Solvent Effects on Excited-State Relaxation Dynamics of Paddle-Wheel BODIPY-Hexaoxatriphenylene Conjugates:Insights from Non-adiabatic Dynamics Simulations

Understanding the excited state dynamics of donor-acceptor(D-A)complexes is of fundamental importance both experimentally and theoretically.Herein,we have first explored the photoinduced dynamics of a recently synthesized paddle-wheel BODIPY-hexaoxatriphenylene(BODIPY is the abbreviation for BF_(2)-chelated dipyrromethenes)conjugates D-A complexes with the combination of both electronic structure calculations and nonadiabatic dynamics simulations.On the basis of computational results,we concluded that the BODIPY-hexaoxatriphenylene(BH)conjugates will be promoted to the local excited(LE)states of the BODIPY fragments upon excitation,which is followed by the ultrafast exciton transfer from LE state to charge transfer(CT).Instead of the photoinduced electron transfer process proposed in previous experimental work,such a exciton transfer process is accompanied with the photoinduced hole transfer from BODIPY to hexaoxatriphenylene.Additionally,solvent effects are found to play an important role in the photoinduced dynamics.Specifically,the hole transfer dynamics is accelerated by the acetonitrile solvent,which can be ascribed to significant influences of the solvents on the charge transfer states,i.e.the energy gaps between LE and CT excitons are reduced greatly and the non-adiabatic couplings are increased in the meantime.Our present work not only provides valuable insights into the underlying photoinduced mechanism of BH,but also can be helpful for the future design of novel donor-acceptor conjugates with better optoelectronic performance.

Excited-State Double Proton Transfer of 1,8-Dihydroxy-2-Naphthaldehyde:a MS-CASPT2//CASSCF Study

Excited-state double proton transfer(ESDPT)is a controversial issue which has long been plagued with theoretical and experimental communities.Herein,we took 1,8-dihydroxy-2-naphthaldehyde(DHNA)as a prototype and used combined complete active space selfconsistent field(CASSCF)and multi-state complete active-space second-order perturbation(MS-CASPT2)methods to investigate ESDPT and excited-state deactivation pathways of DHNA.Three different tautomer minima of S1-ENOL,S1-KETO-1,and S1-KETO-2 and two crucial conical intersections of S1 S0-KETO-1 and S1 S0-KETO-2 in and between the S0 and S1 states were obtained.S1-KETO-1 and S1-KETO-2 should take responsibility for experimentally observing dual-emission bands.In addition,two-dimensional potential energy surfaces(2 D-PESs)and linear interpolated internal coordinate paths connecting relevant structures were calculated at the MS-CASPT2//CASSCF level and confirmed a stepwise ESDPT mechanism.Specifically,the first proton transfer from S1-ENOL to S1-KETO-1 is barrierless,whereas the second one from S1-KETO-1 to S1-KETO-2 demands a barrier of ca.6.0 kcal/mol.The linear interpolated internal coordinate path connecting S1-KETO-1(S1-KETO-2)and S_(1) S0-KETO-1(S1 S0-KETO-2)is uphill with a barrier of ca.12.0 kcal/mol,which will trap DHNA in the S_(1) state while therefore enabling dual-emission bands.On the other hand,the S1/S0 conical intersections would also prompt the S_(1) system to decay to the S_(0) state,which could be to certain extent suppressed by locking the rotation of the C5-C8-C9-O10 dihedral angle.These mechanistic insights are not only helpful for understanding ESDPT but also useful for designing novel molecular materials with excellent photoluminescent performances.