Efficient and Stable Inverted Perovskite Solar Modules Enabled by Solid-Liquid Two-Step Film Formation

A considerable efficiency gap exists between large-area perovskite solar modules and small-area perovskite solar cells.The control of forming uniform and large-area film and perovskite crystallization is still the main obstacle restricting the efficiency of PSMs.In this work,we adopted a solid-liquid two-step film formation technique,which involved the evaporation of a lead iodide film and blade coating of an organic ammonium halide solution to prepare perovskite films.This method possesses the advantages of integrating vapor deposition and solution methods,which could apply to substrates with different roughness and avoid using toxic solvents to achieve a more uniform,large-area perovskite film.Furthermore,modification of the NiO_(x)/perovskite buried interface and introduction of Urea additives were utilized to reduce interface recombination and regulate perovskite crystallization.As a result,a large-area perovskite film possessing larger grains,fewer pinholes,and reduced defects could be achieved.The inverted PSM with an active area of 61.56 cm^(2)(10×10 cm^(2)substrate)achieved a champion power conversion efficiency of 20.56%and significantly improved stability.This method suggests an innovative approach to resolving the uniformity issue associated with large-area film fabrication.

Multi-fluid Eulerian simulation of binary particles mixing and gas–solids contacting in high solids-flux downer reactor equipped with a lateral particle feeding nozzle

The performance of binary particles mixing and gas-solids contacting,which is considered qualitatively to have a significant influence on the heat transfer in internal heated circulating fluidized beds,is carefully investigated by means of a numerical approach in the newly developed high solids-flux downer lignite pyrolyzer(φ0.1 m×6.5 m).Since binary particles are used in this system,a reasonably validated 3 D,transient,multi-fluid model,in which three heat transfer modes relating to the convection,conduction and radiation are considered,is adopted to simulate the flow behavior,temperature profiles as well as volatile contents.The simulation results showed that the solids stream impinges the left wall surface initially and turns towards the right wall in the further downward direction and then shrinks during this process resulting in that the solids concentrate a little more at the central region.In the further downward section of the downer,the particle flow disperses near the right wall and develops uniformly.Meanwhile,the coal phase is slowly heated in the downer and it is found that most of the heat absorbed by the coal is from the convection heat transfer mode.To explore the heat transfer mechanism more quantitatively,two indexes(mixing index and contacting index)are proposed,and it is found that the mixing index initially increased fast and later remained at a relatively flat state.For the contact index,it shows a trend with a first rising and then falling,finally rising continuously.Also,it is found that the convection heat transfer is closely correlated to the contacting status of gas-coal which indicates that the improving of the gas-coal contacting efficiency should be an effective way to strengthen the coal particle heating process.

Electron promoted ZnO for catalytic synthesis of higher alcohols from syngas

Direct conversion of syngas from those non-petroleum carbon resources to higher alcohols are very attractive due to the process simplicity with low energy consumption.However,the reaction always suffers from low yield as well as low selectivity.Herein,effective increase of higher alcohols proportion in the product is realized by direct conversion of syngas over electronically-modulated ZnO semiconductor via Cu doping.It is considered that the lower Fermi level and narrower band gap of catalysts by embedding Cu^(2+)into ZnO lattice could facilitate donor reaction by boosting the process for the reactants to obtain electrons on the catalyst surface for the formation of CH_(x) species and carbon chain growth,in which the Cu doping on ZnO lattice play important role in the promotion of CO adsorption.As a result,4 mol%Cu doped ZnO exhibits a highest C_(2+) OH/ROH fraction of 48.1%.Selectivity of catalysts from straight chain alcohol is better than from branch chain alcohol,which is different from promoted Cu/ZnO based catalyst.However,over-doping of Cu(7 mol%)on ZnO results in the aggregation Cu species on ZnO surface,leading to a sharp decrease of higher alcohols proportion to 3.2%.The results shed light on the nature that a direct correlation between semiconductor Fermi level and synthesis of higher alcohols,and the semiconductor-based catalysts mainly accelerate the hydrogenation reactions by enhancing thermally excited electron transfer.

Improving advantages and reducing risks in increasing cyclone height via an apex cone to grasp vortex end

For a cyclone, it is possible to improve separation efficiency and reduce pressure drop by increasing the cyclone height. However, an exceeded height increase could result in a dramatical drop in separation efficiency. In this study, experimental and computational fluid dynamics simulation results exhibit that the introduction of an apex cone at the dust outlet could avoid the risk of separation efficiency drop but lead to a continuous reducing of the pressure drop. Generally, the optimal cyclone height should be closely related to the natural vortex length. While, when the vortex end contracts into the separation space in the cyclone with an exceeded height, severe back-mixing of particles always occurs, which will result in the decrease of separation efficiency. Herein, it is found that when an apex cone is installed at the dust outlet, the vortex end can be grasped by the cone so as to weaken the back-mixing of particles.Meanwhile, the introduction of this apex cone can enhance the secondary separation to capture the back-mixed particles again so as to protect the efficiency. In addition, it is found that the enhanced secondary separation could come from either the stagnant current of axial velocity in the center or the improved tangential velocity of inner vortex whereas the forcibly extending the length of vortex to exceed its natural length will not significantly increase efficiency.

Fabrication of amorphous FeCoNiCuMnP x high-entropy phosphide/carbon composites with a heterostructured fusiform morphology for efficient oxygen evolution reaction

Amorphous high-entropy materials with abundant defects,coordinatively unsaturated sites,and loosely bonded atoms could exhibit excellent electrocatalytic performance.However,how to fabricate such ma-terials with nanostructure as well as amorphous structure is still full of challenges.In this work,high-entropy metal organic framework(HE-MOF)is employed as the self-sacrificial template to fabricate FeCoNiCuMnP x high-entropy phosphide/carbon(HEP/C)composites.The obtained composite shows a het-erostructured fusiform morphology,in which the HEP is encapsulated by a carbon layer,revealing high electron conductivity as well as rich catalytic active sites for oxygen evolution reaction(OER).Beside,it is found that there is a short-range ordered crystal structure in the amorphous phase,which is bene-ficial for revealing high OER catalytic activity as well as good stability.As a result,the optimum HEP/C composite shows an overpotential 239 mV@10 mA cm^(−2)with a small Tafel slope of 72.5 mV dec^(−1) for catalyzing OER in alkaline solution.

Photocatalytic degradation of tetracycline by copper(I)oxide loaded on Daylily Stalk derived carbon material

In this work,Daylily Stalks derived N doped carbon material(N-DSC)with a high specific surface area was firstly prepared by a chemical activation method,and then cubic Cu_(2)O nanoparticles were combined with the prepared N-DSC to obtain N-DSC/Cu_(2)O composite as the catalyst for the photocatalytic degradation of tetracycline(TC)antibiotics under visible light.It is found that the obtained composite had higher photocatalytic activity than pure Cu_(2)O.Particularly,25 wt%N-DSC/Cu_(2)O composite showed the highest photocatalytic performance with 95%of TC degradation within 100 min and more excellent stability.Combined with various characterizations,it is confirmed that carbon bonds should be conducive to the separation of photoelectron and hole,and the carbon layer with an excellent electrical conductivity on Cu_(2)O can reduce the charge transfer resistance between N-DSC and Cu_(2)O,thereby improving the absorption of visible light and enhancing the photocatalytic activity.Moreover,it is considered that the synergistic effect of photo-generated electron pair in Cu_(2)O and N-DSC could promote the photodegradation efficiency of N-DSC/Cu_(2)O composite.In addition,the active species capture experiment confirmed that·OH and·O_(2)should be the main active species for TC degradation under visible light.This study is expected to provide a novel low-cost photocatalysts for pollutants removal.

Effect of nano Al_(2)O_(3) addition on cycling performance of poly(ether block amide)based solid-state lithium metal batteries

A novel poly(ether block amide)(PEBA)based solid-state polymer electrolyte(SPE)was prepared using a casting method,in which 20wt%lithium(Li)bis-(trifluoromethanesulfonyl)imide(LiTFSI)and aluminum oxide(Al_(2)O_(3))nanoparticles were used as the Li salt and solid plasticizer,respectively.In the case of addition of 3wt%Al_(2)O_(3) nanoparticles,ion conductivity of the obtained PEBA 2533-20wt%LiTFSI-3wt%Al_(2)O_(3) SPE was 3.57×10^(−5) S cm^(−1) at 25°C.Furthermore,the Li symmetrical battery assembled with it showed excellent cycling stability(1000 h)at 0.1 mA cm^(−2).While,the assembled all-solid-state Li/PEBA 2533-20%LiTFSI-3wt%Al_(2)O_(3)/LiFePO 4(areal capacity:0.15 mAh cm^(−2))battery maintained 94.9%of the maximal capacity(133.9 mAh g^(−1@0.1) mA cm^(−2))at 60°C even after 650 cycles with a superior average coulombic efficiency(CE)of 99.84%.By using X-ray photoelectron spectroscope(XPS),self-aggregation layer(SAL)of polyamide 12(PA12)of PEBA 2533 was discovered,which should contribute to promoting the robustness of lithium fluoride(LiF)enriched solid-electrolyte interphase(SEI)layer.In addition,it is considered that the state of interface between SPE and cathode should be the cause of voltage polarization of the full cell.

Application of ionic liquids in CO_(2)capture and electrochemical reduction:A review

As a new type of green solvent with non-volatility,high thermal stability,high conductivity and various adjustable properties,ionic liquid(IL)has been widely used in the capture and electrochemical reduction of carbon dioxide(CO_(2)).To date,many studies have been made to investigate CO_(2)capture by using different types of ILs and CO_(2)electrochemical reduction(CO_(2)ER)with ILs as either electrolyte or other catalytic active components.Some structure-activity relationships between the structure and adsorption or catalytic properties of ILs have been found.Herein,the absorption performances and mechanisms of conventional ILs,amino-functionalized ILs,non-amino functionalized ILs and supported ILs for CO_(2)capture,as well as the performances and action mechanisms of ILs as the electrolyte,electrolyte additive,and/or electrode modifier in the process of CO_(2)ER are summarized.Many researches indicate that the unique interaction between the anion or cation of IL and CO_(2)has a significant contribution to promote the absorption and conversion of CO_(2).However,the ILs used for CO_(2)capture and electrochemical reduction should be further explored.Especially,a more in-depth investigation of the adsorption and catalytic mechanisms with the help of quantum chemical calculation,molecular simulation,and in situ characterization techniques is necessary.It is expected to design and develop more efficient ILs used for CO_(2)capture and conversion on a large scale.

Interface engineering of Fe-Co_(3)N/CoP composite with N-doped C by using soybean:Fabrication of efficient electrocatalysts for oxygen evolution reaction

Soybean can serve as an efficient carbon and nitrogen source for in-situ fabrication of efficient composite electrocatalysts with conductive nitrogen-doped carbon(N-C)material.In this study,the iron-doped cobalt nitride/phosphide(Fe-Co_(3)N/CoP)nanosheet was composited with a conductive N-C material by using soybean as C and N source,as well as NH3 as additional nitrogen source.During the nitridation process of Fe-Co_(3)N,N-C bond was formed as a newly generated Co(Fe)-N-C active sites.Therefore,it fabricates a good microscopic contact interface between the catalyst and carbon material for charge transfer.Besides,the introduction of Fe-CoP by partially phosphating Fe-Co_(3)N further improved the OER activity due to the high catalytic activity of Co sites with high valence state.As a result,the obtained electrocatalyst exhibited overpotentials as low as 285 and 390 mV for supporting 10 and 100 mA/cm􀀀2 current densities.This work indicates that the design of materials with good interfaces could be an effective approach for the preparation of electrocatalysts for water electrolysis.

Electrodeposited iodide ions imprinted polypyrrole@bismuth oxyiodide film for an electrochemically switched renewable extractor towards iodide ions

Effective extraction and regeneration of radioactive iodide is one of urgent concerns for the safe utilization of nuclear energy.As a novel environmentally benign ion separation technique,electrochemically switched ion extraction(ESIE)process can be applied for effective capture and recovery of iodide ions(I^(-)).Herein,a novel kelp seaweed-like core/shell I^(-)imprinted polypyrrole@bismuth oxyiodide(PPy/I^(-)@BiOI)composite film is successfully prepared for the selective I^(-)capture in the ESIE system.It is found that the I^(-)can be easily trapped in the PPy/I^(-)@BiOI film after I^(-)is in situ desorbed from the film by an electrochemical reduction process since it offers particular electroactive binding sites for I^(-)extraction.The I^(-)imprinted PPy/I^(-)@BiOI film displays an extraction capacity as high as 325.2 mg·g^(-1)for I^(-)with favorable stability.In particular,the extraction and desorption of I^(-)is achieved by adjusting the redox potential and the pristine PPy/I^(-)@BiOI film can be regenerated and reused for multiple times without decrease in extraction capacity.It is expected that such a PPy/I^(-)@BiOI film would be useful as an electrochemically switched renewable extractor that could capture and regenerate I^(-)from radioactive water.

Utilization of fruit waste for H_(2)-rich syngas production via steam co-gasification with brown coal

In this work,to efficiently utilize waste fruit and low-rank coal for the hydrogen(H_(2))-rich syngas production,steam co-gasification of banana peel(BP)and brown coal(BC)was studied in a fixed-bed reactor.The results showed that the gasification rate of BC was highly enhanced after mixing it with BP and the obvious synergistic effect was observed in all investigated three mixing weight ratios(i.e.,1:1,1:4,4:1),resulting in a higher carbon conversion as well as a H_(2)-rich gas production yield for the co-gasification.However,the extent of promotion by synergistic effect was affected by the reaction temperature,mixing ratio,and steam amount.It was found that the high potassium(K)species content in the BP provided the catalytic effect not only on water-gas shift reaction but also on tar reforming/cracking,thereby enhancing the gasification of BC.In addition,it is confirmed that steam should be an important factor to promote the synergistic effect and H_(2)-rich gas production.

Metal organic frameworks-based cathode materials for advanced Li-S batteries: A comprehensive review

Li-S batteries(LSBs)have been considering as new and promising energy storage systems because of the high theoretical energy density and low price.Nevertheless,their practical application is inhibited by several factors,including poor electrical conductivity of electrode materials,greatly volumetric variation,as well as the polysulfide formation upon the cycling.To address these problems,it is imperative to develop and design effective and suitable sulfur host anode materials.Metal organic frameworks(MOFs)-based cathode materials,possessing their good conductivity and easy morphology design,have been extensively studied and exhibited enormously potential in LSBs.In this review,a comprehensive overview of MOFs-based sulfur host materials is provided,including their electrochemical reaction mechanisms,related evaluation parameters,and their performances used in LSBs in the past few years.In particular,the recent advances using in-situ characterization technologies for investigating the electrochemical reaction mechanism in LSBs are presented and highlighted.Additionally,the challenges and prospects associated with future research on MOF-related sulfur host materials are discussed.It is anticipated to offer the guidance for the identification of suitable MOFs-based sulfur cathode materials for high-performance LSBs,thereby contributing for the achievement of a sustainable and renewable society.

The swirl and pyrolysis reaction synergistically enhance solid-solid heat transfer and product separation in cyclone pyrolyzer Author links open overlay panel

Cyclone pyrolyzer is a novel type of downer that combines centrifugal force field and double-layer cyclone vortex.Research on transfer behavior is helpful to optimize the pyrolyzer to meet the needs of pyrolysis.In this study,the Computational Particle Fluid Dynamics(CPFD)model is used to analyze the transfer behavior of binary particles,and finds that the swirl and reaction have a synergistic effect.This effect can increase the heating rate of the particles to the range of flash pyrolysis,and its mechanism lies in the flow field structure of the pyrolyzer.Due to the centrifugal force field,the particles gather to the near wall.The rapid swirl,which facilitates intense gas-solid heat transfer,leads to the rapid heating and pyrolysis of biomass particles.As the pyrolysis proceeds,the mass of the biomass particles becomes smaller and they are more easily affected by the gas flow in pyrolyzer.Under the action of gas flow,char particles serve as new heat carrier to form the inner cycle of particles,which strengthens the heating process.The pyrolysis products are discharged from the exhaust port in time with the flow field of the pyrolyzer to achieve separation from the heat carrier and inhibit the occurrence of secondary reactions.

Mn-Co oxide decorated on Cu nanowires as efficient catalysts for catalytic oxidation of toluene

Mn-Co mixed oxides were electrodeposited on Cu nanowires generated on Cu foam(CF)and used for effectively catalytic oxidation of toluene.The physical and chemical properties of the prepared catalysts were characterized by SEM,TEM,XRD,H_(2)-TPR,O_(2)-TPD and XPS.It is found that the Mn-Co mixed metal oxides were uniformly coated on the Cu nanowires by the electrochemical method,whose Mn/Co ratio can be tuned by adjusting the molar ratio of Mn/Co in the initial solution for the electrodeposition.The intimate contact between Mn and Co nanocrystals was found by HRTEM,which is important for realizing synergetic effects on improving catalytic activity.Meanwhile,the formation of the active surface oxygen species and the increase of the active species of Mn^(4+)and Co^(3+)were considered to make significant contribution to the catalytic oxidation of toluene.Mn-Co mixed metal oxide catalysts exhibited higher performance than the single metal oxide,and especially 0.10Mn-0.01Co/CF catalyst with the Mn/Co molar ratio of 10:1 in the initial solution for the electrodeposition achieved the highest catalytic activity with a low toluene conversion temperature(T_(90%))of 251℃,and displayed excellent catalytic stability even in the presence of water vapor.It is expected that such a simply-electrodeposited mixed metal oxides based catalysts could be applied for the oxidation of volatile organic compounds(VOCs)in a practical process.

Stable hetero-metal doped Co-based catalysts prepared by electrodeposition method for low temperature combustion of toluene

A series of hetero-metal(Ni,Mn,and Cu)doped Co-based catalysts were prepared by a unipolar pulse electro-deposition(UPED)method and applied for the catalytic combustion of toluene.It is found that hetero-metal doping significantly influenced the morphology and surface elemental compositions of Co-based catalysts,and the increase in the contents of Ni and Mn elements made a negative influence on the catalyst structure.H_(2)-TPR and O_(2)-TPD analysis results suggested that the hetero-metal doping enhanced the low temperature reducibility and resulted in the formation of lattice defects,which were favorable to generate more easily reducible species and facilitate the oxygen mobility,thereby improved the performance for the catalytic combustion of toluene.Especially,the Co-Cu/NF catalyst performed the best catalytic activity with the lowest toluene conversion temperature of T90 at 248℃,which should be contributed by its low-temperature reducibility,increased surface and lattice oxygen species,and high content of active Co^(3+)species promoted by the interaction of the mixed metal oxides.Moreover,the Co-Cu/NF also performed excellent catalytic stability and high selectivity to CO_(2) in the presence and absence of water vapor for the catalytic combustion of toluene for a long term.

Two-dimensional Ti_(3)C_(2)T_(X)-nanosheets/Cu_(2)O composite as a high-performance photocatalyst for decomposition of tetracycline

Construction of photocatalysts with a Schottky heterojunction could realize highly efficient and stable degradation of organic pollutes in the wastewater.In this work,a precipitation method was used to prepare Ti_(3)C_(2)T_(X)-nanosheets/Cu_(2)O composite photocatalysts with the Schottky heterojunction for the decomposition of tetracycline(TC)antibiotics under visible light.As-prepared photocatalysts were characterized by various techniques such as X-ray diffraction analysis(XRD),High resolution transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS).When the best Ti_(3)C_(2)T_(X)-nanosheets/Cu_(2)O composite was applied for the degradation of TC under visible light,the degradation efficiency reached up to 97.6%only in 50 min.It is considered that superoxide radical(O_(2)^(→))and hole(h^(+))were the main reactive species for the TC degradation,and in the Schottky heterojunction,e^(-)-h^(+)pairs in the catalyst could be transferred and separated effectively,resulting in obviously enhanced photocatalytic efficiency and stability.

Glycerol valorization through production of di-glyceryl butyl ether with sulfonic acid functionalized KIT-6 catalyst

In this work,the etherification of glycerol with n-butanol catalyzed by sulfonic acid functionalized on KIT-6 mesoporous silica(SO_(3)H-KIT-6)was investigated for the production of valuable fuel additives.The SO_(3)H-KIT-6 catalyst was synthesized by co-condensation with different molar ratios of tetraethoxysilane and 3-mercaptopropyl(methyl)di-methoxy silane.The etherification reaction was systematically examined to determine the optimal reaction temperature,reaction time,catalyst loading,and glycerol to n-butanol ratio under autogenous pressure.The maximum glycerol conversion and di-glyceryl n-butyl ether(di-GNBE)selectivity were 59.09 and 51.50%,respectively,when the SO_(3)H-KIT-6 catalyst with the highest acidity was applied.Interestingly,the presence of a methyl group on the catalyst surface prevented glycerol adsorption during the reaction process,leading to the inhibition of undesired product formation.The SO_(3)H-KIT-6 catalyst could be reused up to three times,with only a 13%decrease in glycerol conversion being found.Moreover,the superior performance of the SO_(3)H-KIT-6 catalyst for di-GNBE production was also demonstrated compared with conventional solid acid catalysts including HZSM-5,H-beta zeolite,Amberlyst-35,and Amberlyst-36.

Bio-oil production from pyrolysis of oil palm biomass and the upgrading technologies:A review

Oil palm biomass(OPB)represents major portion of the lignocellulosic waste in Malaysia that can be converted into bio-oil.This review aims to provide important insights in OPB-derived bio-oil production by first discussing the chemical compositions of different OPB and their effects to the bio-oil yield and quality obtained from pyrolysis process,followed by discussing the addition of plastics and catalysts into the pyrolysis for bio-oil upgrading,and lastly summarizing the existing technoeconomic and environmental studies and the potential use of process integration and intensification in this topic.Polypropene(PP),low density polyethylene(LDPE),and high density polyethylene(HDPE)have been commonly used in co-pyrolysis of OPB,which can effectively increase the heating value of bio-oil up to 80%that of diesel.Likewise,acidic,basic,and neutral catalysts have been applied to increase the amount of hydrocarbon and phenol in the bio-oil,further improving the heating value to be comparable to diesel.The bio-oil production from OPB is currently still limited to demonstration scale despite the favorable environmental compatibility and technoeconomic feasibility shown by studies focused on empty fruit bunch(EFB).Several promising advanced pyrolysis processes that integrate other processes such as anaerobic digestion,hydrogen production process,and heat and power generation units as well as the advanced reactor designs are also overviewed here as future innovation of the bio-oil production from OPB,which may play more significant role as the technology matures.

Zeolite-based cracking catalysts for bio-oil upgrading:A critical review

Fast pyrolysis of biomass is an attractive way to produce bio-oil since it can convert most of biomass components directly into liquid fuel. However, the bio-oils obtained from such a fast pyrolysis process always have highly complex oxygenated compounds with high viscosity, serious corrosivity, and rather instability. Thus, before the raw bio-oils are used as fuel or chemical feedstock, they must be upgraded, especially deoxygenated. Cracking of bio-oils over porous solid catalysts such as zeolite-based catalysts at ambient pressure is considered one of effective ways for the bio-oil upgrading, especially in which hydrogen gas is not necessary. Herein, zeolite-based catalysts (mainly HZSM-5 based catalysts) for the upgrading of pyrolysis bio-oils are critically reviewed. The effects of porous structure, acidity and other parameters including biomass type, biomass/catalyst ratio and operation temperature on cracking activity, selectivity, stability and deactivation are summarized. While, the proposed mechanisms on the bio-oil upgrading over the zeolite-based catalysts and the possibility for the application of the developed catalysts in the industrial process are discussed. Furthermore, the main strategies including metal modification, construction of zeolites with a hierarchical structure and synthesis of special morphologies with hollow structure or core/shell structure and nanosheet structures for the improvement of deoxygenation property performance are introduced. It is expected to provide a guidance for the design and fabricate more excellent zeolite-based catalysts and their application for high-quality bio-oil production from fast biomass pyrolysis.

Generation of oxygen vacancies in NiFe LDH electrocatalysts by ultrasound for enhancing the activity toward oxygen evolution reaction

Introduction of vacancies is a promising route to enhance the performance of electrocatalysts by tuning the electronic structure and bonding energy.Here,the influence of ultrasound treatment on the O vacancies formation and interlayer spacing in NiFe layered double hydroxide(LDH)was investigated.It is found that the strong ultrasound treatment results in rich O vacancies on the surface of NiFe LDH,which affect the electrocatalysis performance.Besides,the ultrasound treated NiFe LDH electrocatalysts had a reduced thickness with a hexagonal nanosheet morphology and expanded interlayer distance,which could promote the diffusion of reactant and generated gas.When the obtained defect-rich NiFe LDH electrocatalyst prepared by a 10-min ultrasonic treatment was applied to catalyze oxygen evolution reaction(OER),only 194 mV of overpotential was needed to maintain a current density of 10 mA⋅cm^(-2).