Effect of samarium doping on the activity and sulfur resistance of Ce/MnFeO_(x) catalyst for low-temperature selective catalytic reduction of NO_(x) by ammonia

The self-made MnFeO_(x) catalysts doped with cerium and samarium were prepared by impregnation method for low-temperature selective catalytic reduction(SCR)by NH3.In this work,the surface properties of the series of MnFe-based catalysts were studied.The results indicate Sm-modified catalyst have superior low-temperature SCR activity;NO_(x) conversion maintained at nearby to 100%at 90℃ to 240℃.In addition,The N_(2) selectivity of Sm doping remains above 80%in the range of 60℃ to 150℃.In SO_(2) poisoning test,the NO_(x) conversion can be remained>90%after 10 h of reaction.The XPS,NH_(3)-TPD and H_(2)-TPR results show the catalyst with Sm doping enhances the acid sites and oxidation catalytic sites of mixed oxides serves for improving oxygen vacancies and transfer electrons.In situ diffuse reflaxions infrared Fourier transformations spectroscopy(DRIFTS)results show that NO_(x) is more easily adsorbed on the surface after Sm doping,which provided favorable conditions for the NH_(3)-SCR reaction to proceed.The reaction at the catalyst surface will follow the L-H reaction mechanism by transient reaction test.

Molecular engineering binuclear copper catalysts for selective CO_(2) reduction to C_(2) products

Molecular copper catalysts serve as exemplary models for correlating the structure-reaction-mechanism relationship in the electrochemical CO_(2) reduction(eCO_(2)R),owing to their adaptable environments surrounding the copper metal centres.This investigation,employing density functional theory calculations,focuses on a novel family of binuclear Cu molecular catalysts.The modulation of their coordination configuration through the introduction of organic groups aims to assess their efficacy in converting CO_(2) to C_(2)products.Our findings highlight the crucial role of chemical valence state in shaping the characteristics of binuclear Cu catalysts,consequently influencing the eCO_(2)R behaviour,Notably,the Cu(Ⅱ)Cu(Ⅱ)macrocycle catalyst exhibits enhanced suppression of the hydrogen evolution reaction(HER),facilitating proton trans fer and the eCO_(2)R process.Fu rthermore,we explo re the impact of diverse electro n-withdrawing and electron-donating groups coordinated to the macrocycle(R=-F,-H,and-OCH_3)on the electron distribution in the molecular catalysts.Strategic placement of-OCH_3 groups in the macrocycles leads to a favourable oxidation state of the Cu centres and subsequent C-C coupling to form C_(2) products.This research provides fundamental insights into the design and optimization of binuclear Cu molecular catalysts for the electrochemical conversion of CO_(2) to value-added C_(2) products.

Fe-Mn/Al_2O_3 catalysts for low temperature selective catalytic reduction of NO with NH_3

A series of Fe‐Mn/Al2O3 catalysts were prepared and studied for low temperature selective catalytic reduction （SCR） of NO with NH3 in a fixed‐bed reactor. The effects of Fe and Mn on NO conversion and the deactivation of the catalysts were studied. N2 adsorption‐desorption, X‐ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, H2 temperature‐programmed reduction, NH3 temperature‐programmed desorption, X‐ray photoelectron spectroscopy （XPS）, thermal gravimetric analysis and Fourier transform infrared spectroscopy were used to character‐ize the catalysts. The 8Fe‐8Mn/Al2O3 catalyst gave 99%of NO conversion at 150？？ and more than 92.6%NO conversion was obtained in a wide low temperature range of 90–210？？. XPS analysis demonstrated that the Fe3＋was the main iron valence state on the catalyst surface and the addition of Mn increased the accumulation of Fe on the surface. The higher specific surface area, enhanced dispersion of amorphous Fe and Mn, improved reduction properties and surface acidity, lower binding energy, higher Mn4＋/Mn3＋ratio and more adsorbed oxygen species resulted in higher NO conversion for the 8Fe‐8Mn/Al2O3 catalyst. In addition, the SCR activity of the 8Fe‐8Mn/Al2O3 cata‐lyst was only slightly decreased in the presence of H2O and SO2, which indicated that the catalyst had better tolerance to H2O and SO2. The reaction temperature was crucial for the SO2 resistance of catalyst and the decrease of catalytic activity caused by SO2 was mainly due to the sulfate salts formed on the catalyst.

Influence of coke rate on thermal treatment of waste selective catalytic reduction(SCR)catalyst during iron ore sintering

Waste selective catalytic reduction(SCR)catalyst as a hazardous waste has a significant impact on the environment and human health.In present study,a novel technology for thermal treatment of waste SCR catalyst was proposed by adding it to sinter mix for iron ore sintering.The influences of coke rate on the flame front propagation,sinter microstructure,and sinter quality during sintering co-processing the waste SCR catalyst process were studied.In situ tests results indicated the maximum sintering bed temperature increased at higher coke rate,indicating more liquid phase generated and higher airflow resistance.The sintering time was longer and the calculated flame front speed dropped at higher coke rate.Sinter microstructure results found the coalescence and reshaping of bubbles were more fully with increasing coke rate.The porosity dropped from 35.28%to 25.66%,the pore average diameter of large pores decreased from 383.76μm to 311.43μm.With increasing coke rate,the sinter indexes of tumbler index,productivity,and yield,increased from 33.2%,9.2 t·m^(-2)·d^(-1),28.9%to 58.0%,36.0 t·m^(-2)·d^(-1),68.9%,respectively.Finally,a comprehensive index was introduced to systematically assess the influence of coke rate on sinter quality,which rose from 100 to 200 when coke rate was increased from 3.5%(mass)to 5.5%(mass).

Building up a general selection strategy and catalytic performance prediction expressions of heteronuclear double-atom catalysts for N_(2)reduction

The severe environmental problems and the demand for energy urgently require electrocatalysis to replace Haber-Bosch for the nitrogen reduction reaction(NRR).The descriptors and important properties of single-atom and homonuclear double-atom catalysts have been preliminarily explored,but the relationship between the inherent properties and catalytic activity of heteronuclear double-atom catalysts with better performance remains unclear.Therefore,it is very significant to explore the prediction expressions of catalytic activity of heteronuclear double-atom catalysts based on their inherent properties and find the rule for selecting catalytic centers.Herein,by summarizing the free energy for the key steps of NRR on 55 catalysts calculated through the first-principle,the expressions of predicting the free energy and the corresponding descriptors are deduced by the machine learning,and the strategy for selecting the appropriate catalytic center is proposed.The selection strategy for the central atom of heteronuclear double-atom catalysts is that the atomic number of central B atom should be between group VB and VIIIB,and the electron difference between central A atom and B atom should be large enough,and the selectivity of NRR or hydrogen evolution reaction(HER)could be calculated through the prediction formula.Moreover,five catalysts are screened to have low limiting potential and excellent selectivity,and are further analyzed by electron transfer.This work explores the relationship between the inherent properties of heteronuclear double-atom catalysts and the catalytic activity,and puts forward the rules for selecting the heteronuclear double-atom catalytic center,which has guiding significance for the experiment.

One-pot synthesis of bimetallic CeCu-SAPO-34 for high-efficiency selective catalytic reduction of nitrogen oxides with NH_(3) at low temperature

NH_(3) selective catalytic reduction(SCR) has been widely recognized as a promising technique for reducing nitrogen oxides from diesel vehicle exhausts. High-efficiency SCR catalysts that could perform at low temperatures are essential to denitration. In this work, a series of bimetallic CeCu-SAPO-34 molecular sieves were synthesized by one-step hydrothermal method. The Ce Cu-SAPO-34 maintained good crystallinity and a regular hexahedron appearance of Cu-SAPO-34 after introducing Ce species, while exhibiting a higher specific surface area and pore volume. The as-prepared CeCu-SAPO-34 with 0.02%(mass) Ce constituent exhibited the best catalytic activity below 300℃ and a maximum NO_(x) conversion of 99% was attained;the NO_(x) removal rates of more than 68% and 94% were achieved at 150℃ and 200℃, respectively. And the introduction of cerium species in Cu-SAPO-34 improves the low-temperature hydrothermal stability of the catalyst towards NH_(3)-SCR reaction. Additionally, the introduced Ce species could enhance the formation of abundant weak Br?nsted acid centers and promote the synergistic effect between CuO grains and isolated Cu^(2+) to enhance the redox cycle, which benefit the NH_(3)-SCR reaction.This work provides a facile synthesis method of high-efficiency SCR denitration catalysts towards diesel vehicles exhaust treatment under low temperature.

Resistance to SO_2 poisoning of V_2O_5/TiO_2-PILC catalyst for the selective catalytic reduction of NO by NH_3

A titania pillared interlayered clay（Ti-PILC） supported vanadia catalyst（V2O5/TiO2-PILC） was prepared by wet impregnation for the selective catalytic reduction（SCR） of NO with ammonia. Compared to the traditional V2O5/TiO2 and V2O5-MoO3/TiO2 catalysts, the V2O5/TiO2-PILC catalyst exhibited a higher activity and better SO2 and H2O resistance in the NH3-SCR reaction. Characterization using TPD, in situ DRIFT and XPS showed that surface sulfate and/or sulfite species and ionic SO4^（2-）species were formed on the catalyst in the presence of SO2. The ionic SO4^（2-） species on the catalyst surface was one reason for deactivation of the catalyst in SCR. The formation of the ionic SO4^（2-） species was correlated with the amount of surface adsorbed oxygen species. Less adsorbed oxygen species gave less ionic SO4^（2-） species on the catalyst.

Kinetics of selective catalytic reduction of NO by NH_3 on Fe-Mo/ZSM-5 catalyst

The catalyst of Fe-Mo/ZSM-5 has been found to be more active than Fe-ZSM-5 and Mo/ZSM-5 separately for selective catalytic reduction （SCR） of nitric oxide （NO） with NH3. The kinetics of the SCR reaction in the presence of O2 was studied in this work. The results showed that the observed reaction orders were 0.74-0.99, 0.01-0.13, and 0 for NO, O2 and NH3 at 350-450℃, respectively. And the apparent activation energy of the SCR was 65 kJ/mol on the Fe-Mo/ZSM-5 catalyst. The SCR mechanism was also deduced. Adsorbed NO species can react directly with adsorbed ammonia species on the active sites to form N2 and H2O. Gaseous O2 might serve as a reoxidizing agent for the active sites that have undergone reduction in the SCR process. It is also important to note that a certain amount of NO was decomposed directly over the Fe-Mo/ZSM-5 catalyst in the absence of NH3.

Influence of chromium modification on the properties of MnO_x-FeO_x catalysts for the low-temperature selective catalytic reduction of NO by NH_3

Catalytic properties of MnOx-FeOx complex oxide （hereafter denoted as Mn-Fe） catalysts modified with different loadings of chromium oxide were investigated by using the combination of physico-cbemical techniques, such as N2 physisorption, X-ray diffraction （XRD）, high-resolution transmission electron microscope （HRTEM）, in situ Fourier transform infrared spectroscopy （in situ FT-IR） and temperature-programmed reduction （TPR） and their catalytic activities were evaluated with the selective catalytic reduction （SCR） of NOx by NH3. It was found that with the addition of Cr, more NO could be removed in the low-temperature window （below 120 ℃）. Among the tested catalysts, Mn-Fe- Cr （2 ： 2 ： 1） catalyst exhibited the best catalytic performance at 80 ℃ with the NO conversion higher than 90%. The combination of the reaction and characterization results indicated that （1） the strong interaction among tertiary metal oxides existed in the catalysts when Cr was appropriately added, which made the active components better dispersed with less agglomeration and sintering and the largest BET specific surface area could be obtained; （2） Cr improved the low-temperature reducibility of the catalyst and promoted the formation of the active intermediate （-NH3＋）, which favored the low-temperature SCR reaction.

TiO_2-Supported Binary Metal Oxide Catalysts for Low-temperature Selective Catalytic Reduction of NO_x with NH_3

Binary metal oxide（MnOx-A/TiO2）catalysts were prepared by adding the second metal to manganese oxides supported on titanium dioxide（TiO2）,where,A indicates Fe2O3,WO3,MoO3,and Cr2O3.Their catalytic activity,N2 selectivity,and SO2 poisonous tolerance were investigated.The catalytic performance at low temperatures decreased in the following order：Mn-W/TiO2〉Mn-Fe/TiO2〉Mn-Cr/TiO2〉Mn-Mo/TiO2,whereas the N2 selectivity decreased in the order：Mn-Fe/TiO2〉Mn-W/TiO2〉Mn-Mo/TiO2〉Mn-Cr/TiO2.In the presence of 0.01%SO2 and 6%H2O,the NOx conversions in the presence of Mn-W/TiO2,Mn-Fe/TiO2,or Mn-Mo/TiO2 maintain 98.5%,95.8%and 94.2%, respectively,after 8 h at 120°C at GHSV 12600 h？ 1 .As effective promoters,WO3 and Fe2O3 can increase N2 selectivity and the resistance to SO2 of MnOx/TiO2 significantly.The Fourier transform infrared（FTIR）spectra of NH3 over WO3 show the presence of Lewis acid sites.The results suggest that WO3 is the best promoter of MnOx/TiO2,and Mn-W/TiO2 is one of the most active catalysts for the low temperature selective catalytic reduction of NO with NH3.

Research progress in the SO2 resistance of the catalysts for selective catalytic reduction of NOx

The selective catalytic reduction （SCR） of NOx with NH3 has been proven to be an efficient technology for NOx conversion to N2. However, the catalysts used for SCR usually suffer from the problem of sulfur poisoning which seriously limits their practical application. This review summarized sulfur poisoning mechanisms of various SCR deNG catalysts and strategies to reduce deactivation caused by SO2 such as doping metals, controlling the structures and morphologies of the catalysts, and selecting appropriate supports. The methods and procedures of catalysts preparation and the reaction conditions also have effect on SO2-resistance of the catalysts. Several novel catalyst systems that exhibited good SO2 resistance are also introduced. This paper could provide guidance for the development of highly efficient sulfur-tolerant deNOx catalysts.

Performance of V_2O_5-WO_3-MoO_3/TiO_2 Catalyst for Selective Catalytic Reduction of NO_x by NH_3

The V/O5-WO3-MoOy＇TiO2 honeycomb catalyst was prepared with industrial grade chemicals. The structural and physico-chemical properties were analyzed with X-ray diffraction （XRD）, scanning electron micrograph （SEM） and mercury porosimetry. The NOx conversion and durability were investigated on a pilot plant test set under the actual operational conditions of a coal fired boiler. The catalyst monolith had good formability with mass per- centage of V ： W ： Mo ： TiO2 ： fiber glass = 1 ： 4.5 ： 4.5 ： 72 ： 18. Vanadium, tungsten and molybdenum species were highly dispersed on anatase TiO2 without causing the transformation of anatase TiO2 to ruffle by calcining under a current of air at 450℃ for 4.5 h, but there were some degrees of crystal distortion. The catalyst particle sizes were almost uniform with close pile-up and the pore structure was regular with complete macro-pore formation and large specific surface area. The NOx conversion was sensitive to temperature but nearly insensitive to NH3. The catalyst showed strong adaptability to NOx concentration with activity above 80% in the range of 615 1640 mg.m-3. Within the range of 720-8640 h continuous operation, the NOx conversion dropped at a rate of about 1% reduction per 600 h.

Experimental and Kinetic Study of Selective Catalytic Reduction of NO with NH_3 over CuO/Al_2O_3/Cordierite Catalyst

The CuO/γ-Al2O3/cordierite catalyst, after being sulfated by sulfur dioxide (SO2) at 673 K, exhibits high activities for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH3) at 573-723 K. The intrinsic kinetics of SCR of NO with NH3 over CuO/γ-Al2O3/cordierite catalyst has been measured in a fixed-bed reactor in the absence of internal and external diffusions. The experimental results show that the reaction rate can be quantified by a first-order expression with activation energy Eá of 94.01 kJ·mol-1 and the corresponding p re-exponential factor A′ of 3.39×108 cm3·g-1·s-1 when NH3 is excessive. However, when NH3 is not enough, an E ley-Rideal kinetic model based on experimental data is derived with Ea of 105.79 kJ·mol-1, the corresponding A of 2 .94×109 cm3·g-1·s-1, heat of adsorption-Hads of 87.90 kJ·mol-1 and the corresponding Aads of 9.24 cm3·mol-1. The intrinsic kinetic model obtained was incorporated in a 3D mathematical model of monolithic reactor, and the agreement of the prediction with experimental data indicates that the present kinetic model is adequate for the reac-tor design and engineering scale-up.

Transfer and Reaction Performances of Selective Catalytic Reduction of NzO with CO over Monolith Catalysts

This work tries to identify the relationship between geometric configuration of monolith catalysts, and transfer and reaction performances for selective catalytic reduction of N2O with CO. Monolith catalysts with five different channel shapes (circle, regular triangle, rectangle, square and hexagon), was investigated to make a comprehensive comparison of their pressure drop, heat transfer Nu number, mass transfer Sh number and N2O conversion. It was found that monolith catalysts have a much lower pressure drop than that of traditional packed bed, and for monolith catalysts with different channel shapes, pressure drop decreases in the order of regular triangle > rectangle > square > hexagon > circle. The order of Nu is in regular triangle > rectangle ≈ square > hexagon > circle, similar to that of Sh. N2O conversion follows the order of regular triangle > rectangular ≈ square ≈ circle > hexagon. The results indicate that chemical reaction including internal diffusion is the controlling step in the selective catalytic reduction of N2O removal with CO. In addition, channel size and gas velocity also have influence on N2O conversion and pressure drop.

Selective catalytic reduction of NO with NH_3 over sol-gel-derived CuO-CeO_2-MnO_x/γ-Al_2O_3 catalysts

Granular CuO-CeO2-MnOx/γ-Al2O3 catalysts were synthesized by the sol-gel method. The performance of the CuO-CeO2-MnOx/γ-Al2O3 catalysts for the selective catalytic reduction (SCR) was studied in a fixed bed system. Preliminary tests were carried out to analyze the behavior of NH3 and NO over catalyst in the presence of oxygen. The optimum temperature range for SCR over the CuO-CeO2-MnOx/γ-Al2O3 catalysts is 300-400 ℃ . The catalysts maintain nearly 100% NO conversion at 350 ℃. The NH3 oxidation experiments show that both NO and N2O are produced gradually with the increase of temperature. The catalysts in this experiment have a stronger oxidation property on NH3, which improves the denitrification activity at low temperature. The over-oxidation of NH3 at high temperature is the main cause leading to a decrease in the NO conversion. The NH3 and NO desorption experiments show that NH3 and NO can be adsorbed on CuO-CeO2-MnOx/γ-Al2O3 granular catalysts. The transient response of NH3 and NO indicates that the SCR reaction proceeds in accordance with the Eley-Rideal mechanism. The adsorbed NO has little influence on the denitrification activity in SCR process.

The Preparation of Mn-Fe/CNTs Catalyst at the Low-Temperature Selective Catalytic Reduction of NO with NH₃

The metal oxide catalyst was prepared by loading MnOx and FeOx on carbon nano-tubes (CNTs) with impregnation method. Then the catalyst was characterized by BET and XPS, and the effect of adding FeOx on MnOx/CNTs catalyst at the low-temperature selective catalytic reduction of NO with NH3 was investigated. The results showed that the active components were loaded suc-cessfully and easily on the carriers by impregnation. The Mn-Fe/CNTs catalyst was chose 10% Fe(NO3)3 solution to impregnate Mn-Fe/CNTs. The species of active components loaded on the catalyst were Fe2O3. The different concentration of impregnant solution played an important role for NO conversion in SCR with NH3. With the increase of the concentration of impregnant solution, the NO conversion of catalysts was increasing initially then decreasing.

Low-Temperature Denitrification Performance of Cu2O/Activated Carbon Catalysts for Selective Catalytic Reduction of NOx by CO

To improve the denitrification performance of carbon-based materials for sintering flue gas,we prepared a composite catalyst comprising coconut shell activated carbon(AC)modified by thermal oxidation air.The microstructure,the specific surface area,the pore volume,the crystal structure,and functional groups presented in the prepared Cu2O/AC catalysts were thoroughly characterized.By using scanning electron microscopy(SEM),nitrogen adsorption/desorption isotherms,Fourier-transform infrared(FTIR)spectroscopy and X-ray diffractometry(XRD),the effects of Cu2O loading and calcination temperature on Cu2O/AC catalysts were investigated at low temperature(150℃).The research shows that Cu on the Cu2O/AC catalyst is in the form of Cu2O with good crystalline performance and is spherical and uniformly dispersed on the AC surface.The loading of Cu2O increases the active sites and the specific surface area of the reaction gas contact,which is conducive to the rapid progress of the carbon monoxide selective catalytic reduction(CO-SCR)reaction.When the loading of Cu2O was 8%and the calcination temperature was 500℃,the removal rate of NOx facilitated by the Cu2O/AC catalyst reached 97.9%.These findings provide a theoretical basis for understanding the denitrification of sintering flue gas.

Transition Metal Doped MnO_x-CeO₂Catalysts by Ultrasonic Immersing for Selective Catalytic Reduction of NO with NH₃at Low Temperature

Transition metals doped Mn-based catalysts were prepared via ultrasonic immersing method for the selective catalytic reduction (SCR) of NOx from fuel gas. The Catalysts’ DeNOx efficiency and tolerance to sulfur were investigated in the paper. XRD results demonstrate high dispersion of Mn, Ce and M (Pr, Y, Zr, W) elements on TiO2 carrier, which is favor for reduction of active materials content. Mn-Ce-W catalyst presents uniform particle size about 500 nm to 800 nm from SEM pictures and shows the best NOx conversion of 93.2% at 200°C and 98.4% at 250°C, respectively. Sulfur tolerance analysis indicated that transition metals M can improve the catalysts’ performance when 0.01% SO2 exists in the fuel gas, because metal doping into the Mn-Ce catalyst can inhibit the sulfate deposition, especially metal sulfate, on the catalyst, which can be seen from the Fourier infrared spectrum.

Suppressing byproduct formation for high selective CO_(2) reduction over optimized Ni/TiO_(2) based catalysts

One of the challenges for catalytic CO_(2)reduction is to control product selectivity,and new findings that can modify selectivity would be transformative.Herein,two kinds of TiO_(2)(homemade and commercial)with the same crystal phase but different surface properties are chosen as supports to prepare Ni-based catalysts for CO_(2)reduction,which show distinctly different product selectivity for CO_(2)reduction to CH_(4) or CO,as well as the CO_(2)conversion.The catalysts based on the homemade TiO_(2)support are highly selective for CH_(4) formation,while the latter ones are about 100%selective for CO formation under the same reaction conditions.In addition,the former ones are much active(more than 3 times)than the latter ones.We found that the collaborative contribution of Ti^(3+)and Ni^(2+)species and the electronic metal-support interactions effect maybe the main driving force behind for determining the product selectivity.Methane is almost exclusively produced over the catalysts with abundant Ti^(3+)and Ni^(2+)species and greater electronic metal-support interaction,otherwise,it will give priority to CO generation.The addition of CeO_(2)can reduce the Ni particle size and improve the dispersion of Ni nanoparticles,as well as create more Ti^(3+)species,contributing to the enhancement of CO_(2)conversion,but shows a negligible effect on product selectivity.Furthermore,the in situ DRIFT experiments and kinetic experiments indicate that the CO route is probably involved in the CO_(2)reduction process over the homemade Ni-CeO_(2)/TiO_(2)-CO catalyst with abundant Ti^(3+)and Ni^(2+)species and a strong electronic transform effect.

The role of morphology on the electrochemical CO_(2) reduction performance of transition metal-based catalysts

The continued increase in population and the industrial revolution have led to an increase in atmospheric carbon dioxide(CO_(2)) concentration. Consequently, developing and implementing effective solutions to reduce CO_(2) emissions is a global priority. The electrochemical CO_(2) reduction reaction(CO_(2)RR) is strongly believed to be a promising alternative to fossil fuel-based technologies for the production of value-added chemicals. So far, the implementation of CO_(2)RR is hindered by associated electrochemical reactions, such as low selectivity, hydrogen evolution reaction(HER), and additional overpotential induced in some cases. As a result, it is necessary to conduct a timely evaluation of the state-of-the-art strategies in CO_(2)RR, with a focus on the engineering of the electrocatalytic systems. Catalyst morphology is one factor that plays a critical role in overcoming these drawbacks and significantly contributes to enhancing product selectivity and Faradaic efficiency(FE). This review article summarizes the recent advances in the rational design of electrocatalysts with various morphologies and the influence of these morphologies on CO_(2)RR. To compare literature findings in a meaningful way, the article focuses on results reported under a well-defined period and considers the first three rows of the d-block metal catalysts. The discussion typically covers the design of nanostructured catalysts and the molecular-level understanding of morphology-performance relationship in terms of activity, selectivity, and stability during CO_(2) electrolysis. Among others, it would be convenient to recommend a comprehensive discussion on the morphologies of single metals and heterostructures, with a detailed emphasis on their impact on CO_(2) conversion.