Experimental constraints on the formation of oxychlorine species by UV irradiation and mechanical pulverization on the lunar surface

Perchlorate and chlorate are present in various extraterrestrial celestial bodies throughout the solar system,such as Mars,the moon,and asteroids.To date,the origin mechanisms of perchlorate and chlorate on the Martian surface have been well-established;however,relatively little attention has been cast to airless bodies.Here,we experimentally investigated the potential oxidation mechanisms of chloride to chlorate and perchlorate,such as ultraviolet irradiation under H_(2)O-and O_(2)-free conditions and mechanical pulverization processes.Individual minerals,olivine,pyroxene,ilmenite,magnetite,TiO_(2)and anhydrous ferric sulfate,and lunar regolith simulants(low Ti,CLRS-1;high-Ti,CLRS-2)and their metallic iron(Fe^( 0))bearing counterparts were examined.We found that pulverization of dry matrix material-halite mixtures,even in the presence of O_(2),does not necessarily lead to perchlorate and chlorate formation without involving water.Under photocatalytic and H_(2)O and O_(2)-free conditions,olivine and pyroxene can produce oxychlorine(ClO_(x)^(−))species,although the yields were orders of magnitude lower than those under Martian-relevant conditions.Nanophase-Fe^(0)particles in the lunar regolith and the common photocatalyst TiO_(2)can facilitate the ClO_(x)^(−)formation,but their yields were lower than those with olivine.The oxides ilmenite and magnetite did not efficiently contribute to ClO_(x)^(−)production.Our results highlight the critical role of H_(2)O in the oxidation chloride to chlorate and perchlorate,and provide essential insights into the environmental influence on the formation of oxychlorine species on different celestial bodies.

A versatile strategy to activate self-sacrificial templated Li_(2)MnO_(3) by defect engineering toward advanced lithium storage

Despite the dazzling theoretical capacity,the devasting electrochemical activity of Li_(2)MnO_(3)(LMO)caused by the difficult oxidation of Mn4+impedes its practical application as the lithium-ion battery(LIB)cathode.The efficacious activation of the Li_(2)MnO_(3) by importing electrochemically active Mn3+ions or morphological engineering is instrumental to its lithium storage activity and structural integrity upon cycling.Herein,we propose a conceptual strategy with metal-organic frameworks(MOFs)as self-sacrificial templates to prepare oxygen-deficient Li_(2)MnO_(3)(O_v-LMO)for exalted lithium storage performance.Attributed to optimized morphological features,LMO materials derived from Mn-BDC(H_(2)BDC=1,4-dicarboxybenzene)delivered superior cycling/rate performances compared with their counterparts derived from Mn-BTC(H_(3)BTC=1,3,5-benzenetricarboxylicacid)and Mn-PTC(H_(4)PTC=pyromellitic acid).Both experimental and theoretical studies elucidate the efficacious activation of primitive LMO materials toward advanced lithium storage by importing oxygen deficiencies.Impressively,O_v-LMO derived from Mn-BDC(O_v-BDC-LMO)delivered intriguing reversible capacities(179.2 mA h g^(-1)at 20 mA g^(-1)after 200 cycles and 100.1 mA h g^(-1)at 80 mA g^(-1)after 300 cycles),which can be attributed to the small particle size that shortens pathways for Li+/electron transport,the enhanced redox activity induced by abundant oxygen vacancies,and the optimized electronic configuration that contributes to the faster lithium diffusivity.This work provides insights into the rational design of LMO by morphological and atomic modulation to direct its activation and practical application as an advanced LIB cathode.

Regulating Electron-Hole Separation to Promote the Photocatalytic Property of BiOBr_1−xI_x/BiOBr Local Distorted Hierarchical Microspheres

In this work, hierarchical BiOBr1−xIx/BiOBr heterojunction photocatalyst with a microsphere morphology was synthesized by a facile solvothermal process. It demonstrated that the local structure of the photocatalysts was highly distorted due to the substitution of bromide ions by iodine ions. The photocatalytic properties were evaluated by the photodecomposition of aqueous phenol solution under visible-light irradiation. The results indicated that all the composite photocatalysts exhibited high photocatalytic activity. In particularly, the BiOBr1−xIx/BiOBr (x = 0.25) sample exhibited over 92% degradation efficiency of phenol within 150 min, which is 24.6 and 3.08 fold enhancement in the photocatalytic activity over the pure phased BiOBr and BiOI, respectively. Moreover, this excellent photocatalytic property can be expanded to other colorless organic contaminants, verifying the common applicability of BiOBr1−xIx/BiOBr (x = 0.25) as an excellent visible-light photocatalyst for organics decomposition. The significant improvement in the photocatalytic activity can be explained by the high efficiency of charge separation due to the enhancement in the internal electric fields and band match that comes from the local structure distortion. This work provides valuable information for the design of highly active photocatalysts toward the environmental remediation.

Surface modulation of MoS_(2)/O-ZnIn_(2)S_(4) to boost photocatalytic H_(2)evolution

To realize the continuous production of hydrogen energy,the efficient photocatalysts are required in the heterogeneous reaction for water splitting.Herein,we reported a surface modulation strategy,via doping oxygen atoms to tune the surface state of ZnIn_(2)S_(4)nanosheets with cocatalyst MoS_(2)modification,to enhance water adsorption and surface catalytic reaction for boosting the photocatalytic activity.Consequently,MoS_(2)/O-ZnIn_(2)S_(4)photocatalysts showed a remarkably superior photocatalytic H_(2)production performance of 4.002 mmol g^(-1)h^(-1)and an apparent quantum yield(AQY)of~2.53%,5.4 folds higher than ZnIn_(2)S_(4).Using operando infrared spectroscopy and DFT calculation,we revealed the dynamic structural evolution,as well as the active sites for water adsorption and the catalytic reaction at the MoS_(2)/O ZnIn_(2)S_(4)interface.This work reveals the effect of surface modulation on the photocatalytic activity for MoS_(2)/O-ZnIn_(2)S_(4)and offers a feasible method to devise excellent nanomaterial photocatalysts for H_(2)production.

Spontaneous polarization enhanced bismuth ferrate photoelectrode:fabrication and boosted photoelectrochemical water splitting property

In this paper,the fabrication of a highly orientated Bi_(2)Fe_(4)O_(9)(BFO)photoelectrode in the presence of two-dimensional(2D)graphene oxide(GO)was reported.It was found that the GO can be used as a template for controlling the growth of BFO,and the nanoplate composites of BFO/reduced graphene oxide(RGO)with a high orientation can be fabricated.The thickness of the nanoplates became thinner as the ratio of GO increased.As a result,the ferroelectric spontaneous polarization unit arranges itself in the space in a periodic manner,leading to the formation of a polarization field along a special direction.Therefore,the created built-in electric field of the nanoplate composites of BFO/RGO is improved upon the increase of the amount of RGO.As expected,carrier separation is enhanced by the built-in electric field,therefore substantially enhancing the photoelectrochemical(PEC)activity of water splitting compared to pure BFO under the irradiation of visible-light.