Interface engineering via temperature-dependent self-transformation on SnS_(2)/SnS for enhanced piezocatalysis

Heterojunction has been widely used in vibration-driven piezocatalysis for enhanced charges separation,while the weak interfaces seriously affect the efficiency during mechanical deformations due to prepared by traditional step-by-step methods.Herein,the intimate contact interfaces with shared S atoms are ingeniously constructed in SnS_(2)/SnS anchored on porous carbon by effective interface engineering,which is in-situ derived from temperature-dependent self-transformation of SnS_(2).Benefiting from intimate contact interfaces,the piezoelectricity is remarkably improved due to the larger interfacial dipole moment caused by uneven distribution of charges.Importantly,vibration-induced piezoelectric polarization field strengthens the interfacial electric field to further promote the separation and migration of charges.The dynamic charges then transfer in porous carbon with high conductivity and adsorption for significantly improved piezocatalytic activity.The degradation efficiency of bisphenol A(BPA)is 6.3 times higher than SnS_(2) and H_(2) evolution rate is increased by 3.8 times.Compared with SnS_(2)/SnS prepared by two-step solvothermal method,the degradation efficiency of BPA and H2 evolution activity are increased by 3 and 2 times,respectively.It provides a theoretical guidance for developing various multiphase structural piezocatalyst with strong interface interactions to improve the piezocatalytic efficiency.

O2-Oxidation of Cyanomethylene Radical:Infrared Identification of Criegee Intermediates syn-and anti-NCC(H)OO

Cyanomethylene radical(HCCN)is an important intermediate in the nitrile chemistry in both the earth’s and the Titan’s atmosphere.Despite that the mechanism for the oxidation of HCCN has been already computationally explored,the key Criegee intermediate,NCC(H)OO,remains unobserved yet.By photolyzing mixtures(1:50:1000)of either HC(N2)CN/O2/N2(266 nm)or HCCNCO/O2/N2(193 nm)at 15.0 K,the elusive carbonyl oxides NCC(H)OO,in syn-and anti-conformations,have been generated and characterized with IR spectroscopy.The spectroscopic identification is supported by ^18O-labeling experiments and the quantum chemical calculations at the BP86/6-311++G(3df,3pd)level.Upon subsequent UV-light irradiation,both conformers of NCC(H)OO further react with O2 and yield NCC(O)H and O3,whereas,the dioxirane isomer HC(O2)CN,which is lower than syn-NCC(H)OO by 23.7 kcal/mol at the CCSD(T)-F12a/aug-cc-pVTZ//BP86/6-311++G(3df,3pd)level,was not observed experimentally.

Hierarchical AgAu alloy nanostructures for highly efficient electrocatalytic ethanol oxidation

The ethanol oxidation reaction is a significant anodic reaction for direct alcohol fuel cells.The most commonly used catalysts for this reaction are Pt‐based materials;however,Pt‐based electrocatalysts cause carbon monoxide poisoning with intermediates before the complete transformation of alcohol to CO_(2).Herein,we present hierarchical AgAu bimetallic nanoarchitectures for ethanol electrooxidation,which were fabricated via a partial galvanic reduction reaction between Ag and HAuCl_(4).The ethanol electrooxidation performance of the optimal AgAu nanohybrid was increased to 1834 mA mg^(‒1),which is almost 10 times higher than that of the pristine Au catalyst(190 mA mg^(‒1))in alkaline solutions.This was achieved by introducing Ag into the Au catalyst and controlling the time of the replacement reaction.The heterostructure also presents a higher current density than that of commercial Pt/C(1574 mA mg^(‒1)).Density functional theory calculations revealed that the enhanced activity and stability may stem from unavoidable defects on the surface of the integrated AgAu nanoarchitectures.Ethanol oxidation reactions over these defects are more energetically favorable,which facilitates the oxidative removal of carbonaceous poison and boosts the combination with radicals on adjacent Au active sites.

Preparation of hierarchical CuO@TiO_2 nanowire film and its application in photoelectrochemical water splitting

A new kind of self-standing CuO@TiO2 nanowires (NWs) film with hierarchical feature was prepared by a three-step protocol consisting of hydrothermal reaction, electroless plating, and branched growth processes. This heterostructured CuO@TiO2 NWs film demonstrates the favorable physical properties in the photoelectrochemical cell (PEC) water splitting, such as the hierarchical surface, the extended optical absorption range, and the rapid interface charge transfer kinetics. Under the illumination of the simulated solar light, the pristine TiO2 NWs film only attains a photocurrent density of 0.12 mA/cm2 at 1.0 V versus reversible hydrogen electrode (RHE). Significantly, the CuO@TiO2 NWs film can yield a dramatically increased photocurrent density of 0.56 mA/cm2 at the same applied voltage. Furthermore, amperometric I?t tests of the CuO@TiO2 NWs film reveal satisfactory stability. All the above characteristics of this heterostructured CuO@TiO2 NWs film indicate its great potential in the water splitting applications with solar visible light.

A trace of Pt can significantly boost RuO_(2) for acidic water splitting

The development of highly potential electrocatalysts for acidic water electrolysis is particularly desirable for many energy‐related processes.Herein,we demonstrated a versatile strategy to activate and stabilize RuO_(2)‐based electrocatalyst for acidic water splitting by a trace of Pt,where Pt plays an essential role in promoting oxygen evolution reaction(OER),and can simultaneously act as the active site for hydrogen evolution reaction(HER).Compared with pure Ru oxide nanosheet assemblies(Ru ONAs),the“5%Pt‐containing”Ru ONAs(5%Pt‐Ru ONAs)achieve much enhanced OER activity in 0.5 and 0.05 mol/L H_(2)SO_(4),with much lower overpotentials of 227 and 234 mV at 10 mA cm^(‒2),respectively.Experimental and theoretical analyses reveal that the atomically dispersed Pt incorporating into RuO_(2)lattice is conducive to increasing the concentration of O vacancies,which effectively enhances the interaction with reaction intermediate and thus lowers the energy barrier for the formation of OOH*.Moreover,benefited from the presence of Pt,the formation of RuO_(2)is more achievable when proper annealing is applied.In addition to OER,due to the presence of active Pt,the HER performance of 5%Pt‐Ru ONAs can also be ensured,thereby realizing efficient acidic overall water splitting.Finally,the excellent activity can also be achieved without sacrificing stability.This work highlights an attractive strategy for designing active and stable RuO_(2)‐based electrocatalysts for acidic overall water splitting.

UBD教育理论融合核心素养的教学——以“硫及其化合物”为例

UBD理论(理解为先)注重以教学预期目标为导向,通过先预设评估标准,再设计学习活动,最终达成对科学本质理解的学习目标。以“硫及其化合物教学”为例,采用UBD教学理论进行教学设计,注重学生核心素养的发展,最后根据实际教学活动和效果,提出几点展望。