Journal of Catalysis最新文献

{"title":"Catalytic utilization of transition, post-transition and rare earth metal-substituted brownmillerite-related solids for the continuous-flow hydrogenations of CO2 and furfural into synthetic fuels","authors":"Rebeka Mészáros ,&nbsp;Adél Anna Ádám ,&nbsp;Kornélia Baán ,&nbsp;Ádám Pitó ,&nbsp;Gyula Halasi ,&nbsp;János Kiss ,&nbsp;András Sápi ,&nbsp;Zoltán Kónya ,&nbsp;Ákos Kukovecz ,&nbsp;Márton Szabados","doi":"10.1016/j.jcat.2025.116282","DOIUrl":"10.1016/j.jcat.2025.116282","url":null,"abstract":"<div><div>Brownmillerite-type perovskites (or called dicalcium ferrite derivatives, Ca₂Fe_1.4M_0.6O_x), as excellent candidates for Earth-abundant catalysts, were tested in gas- (CO₂) and liquid-phase (furfural) hydrogenations for the first time. Preparation of precursor forms of catalysts using a variety of metals M(III) = Al, Sc, Cr, Mn, Fe, Co, Ga, Y, Rh, Sb, In, La, Yb and Bi was attempted, and the results show that incorporation of metals larger than Sc(III) was not possible without the formation of extralattice phases. Dicalcium ferrite derivatives formed by calcination of hydrocalumite-based layered double hydroxides, interestingly, the appearance of the layered double hydroxides correlated well with the successful formation of brownmillerites in most cases. <em>In situ</em> reduced forms (containing Fe(0) and iron carbide active phases) of most materials performed well with and without impregnation of nickel nanoparticles in thermocatalytic CO₂ reduction. High CO selectivities between 60 and 99 % were measured, resulting from the combination of the following reaction pathways: hydrogen-assisted CO₂ dissociation, thermal decomposition of formyl and formate intermediates and reverse water gas shift reactions of carboxylate products. <em>Ex situ</em> reduced brownmillerites (or even hydrocalumites) with M = Fe and Rh possessed outstanding and robust activity in furfural reduction (by simultaneous direct and transfer hydrogenation), and furfuryl alcohol selectivity was consistently full in the scale-up tests. In these hydrogenations to sustainable fuels, performance of brownmillerite-based catalysts has been able to outperform many of the transition (Co, Ni, Cu) and noble metal (Ru, Pd, Pt) catalysts known from the literature, highlighting the potential of these cheap and readily producible materials.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116282"},"PeriodicalIF":6.5,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144479635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Work-function-mediated unidirectional charge flow enables 139-fold enhanced photocatalytic hydrogen evolution on g-C3N4","authors":"Yiming Zhang ,&nbsp;Yunpeng Zhang ,&nbsp;Jingang Yang ,&nbsp;Chenchen Feng ,&nbsp;Shibo Shao ,&nbsp;Peisen Li ,&nbsp;Qizheng Dong ,&nbsp;Xusheng Wang","doi":"10.1016/j.jcat.2025.116296","DOIUrl":"10.1016/j.jcat.2025.116296","url":null,"abstract":"<div><div>Suppressing photogenerated carrier recombination remains a pivotal challenge in photocatalyst design. In this work, we strategically integrate Co₃O₄ as a hole-extracting layer and Ni as an electron-trapping cocatalyst onto graphitic carbon nitride (g-C₃N₄), establishing a work-function-gradient-driven charge transport pathway along the Co₃O₄ → g-C₃N₄ → Ni directional cascade, resulting enhanced carrier concentration and charge migration kinetics. The optimized 1.5 %Ni-1 %Co₃O₄-C₃N₄ achieves a remarkable photocatalytic hydrogen evolution rate of 16.71 μmol h⁻¹, surpassing 1 %Co₃O₄-C₃N₄ (5.17 μmol h⁻¹), 1.5 %Ni-C₃N₄ (1.64 μmol h⁻¹) and g-C₃N₄ (0.12 μmol h⁻¹) by 3.2, 10.2 and 139.2 times, with robust stability over multiple cycles. Photoelectric characterizations confirm accelerated charge separation via synergistic electron transfer by Ni electron sinks and Co₃O₄ hole extractor. Density functional theory reveals work function gradient of Co₃O₄, g-C₃N₄, and Ni driving unidirectional electron flow from Co₃O₄ to Ni active sites via g-C₃N₄ as bridge, while an upward-shifted Ni d-band center and optimized hydrogen adsorption energy (ΔG_*H) of 1.5 %Ni-1 %Co₃O₄-C₃N₄ enhance *H reduction kinetics. This work establishes a work-function-gradient based strategy for advancing solar-to-hydrogen conversion technologies.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116296"},"PeriodicalIF":6.5,"publicationDate":"2025-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144371203","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanistic insights into nitrate electroreduction on CuNi alloys: d-band center modulation of key intermediates","authors":"Qiuling Jiang ,&nbsp;Ying Wang ,&nbsp;Zhijian Wu","doi":"10.1016/j.jcat.2025.116287","DOIUrl":"10.1016/j.jcat.2025.116287","url":null,"abstract":"<div><div>Electrochemical nitrate reduction reaction to ammonia (NO₃RR) is a promising alternative to the traditional Haber-Bosch process for NH₃ synthesis. The development of efficient electrocatalysts is crucial for this process. Copper-nickel alloy (CuNi) catalysts demonstrate excellent catalytic performance over pristine copper (Cu) and pristine nickel (Ni) catalysts, and it is noted that Ni incorporation significantly improves nitrate removal efficiency while suppressing undesirable nitrite formation for NO₃RR. However, the reaction mechanism of NO₃RR on CuNi catalysts remains unclear, particularly regarding the role of Ni incorporation. In this study, constant-potential method calculations were applied to CuNi(1 1 1) catalysts (Cu₃Ni₁(1 1 1), Cu₂Ni₂(1 1 1), and Cu₁Ni₃(1 1 1) with Cu:Ni atomic ratios of 3:1, 1:1, and 1:3, respectively) to understand their enhanced NO₃RR performance compared to pristine Cu(1 1 1) and pristine Ni(1 1 1) catalysts. The potential-dependent adsorption energetics reveal the enhanced co-adsorption of NO₃* and H* facilitates nitrate deoxidation-protonation and improves Faradic efficiency, while the strengthened NO₂* binding simultaneously promotes its further reduction rather than desorption. Microkinetic analyses identify the dominant surface intermediates, and the simulated NH₃ formation current densities exhibit highly consistent with experimental trends. Furthermore, the electronic structure analyses elucidate that the <em>d</em>-band center, optimized near Cu:Ni = 1:1, modulates the binding strengths of key intermediates and reduces activation barriers, thereby suppressing nitrite formation while promoting selective ammonia formation. These fundamental insights not only rationalize previously reported experimental phenomena but also provide design principles for developing efficient NO₃RR electrocatalysts.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116287"},"PeriodicalIF":6.5,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144371204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrochemical CO2 reduction by Mn-mesbpy complex: Tuning redox properties and mechanistic switching via ligand substitution","authors":"Miho Isegawa","doi":"10.1016/j.jcat.2025.116290","DOIUrl":"10.1016/j.jcat.2025.116290","url":null,"abstract":"<div><div>Density functional theory (DFT) calculations were used to investigate the effects of electron-donating and electron-withdrawing substituents on the mesbpy ligand of Mn-based complexes employed in the electrochemical reduction of CO₂. The influence of these substituents on reduction potentials, CO₂ binding affinities, and the overall catalytic mechanism was systematically examined. DFT results indicated that Mn complexes bearing electron-donating groups (–CH₃, –OH), neutral groups (–H), and moderately electron-withdrawing groups (–F) can bind CO₂ in the two-electron-reduced state. In contrast, Mn complexes with strongly electron-withdrawing substituents (–CF₃, –CN) facilitate the initial reduction step but fail to bind CO₂ at the same redox state, thus requiring a third electron for activation. However, these complexes become energetically inefficient as catalysts due to the high energy demand associated with the three-electron reduction. The mechanistic insights presented here, which distinguish Mn complexes bearing electron-donating or moderately electron-withdrawing substituents from those with strongly electron-withdrawing groups, provide valuable design principles for the development of energy-efficient Mn-based CO₂ reduction catalysts.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116290"},"PeriodicalIF":6.5,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144371253","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanistic crossover in photocatalytic transfer hydrogenation of nitroaromatics upon switching from static to periodic illumination","authors":"Sie Shing Wong ,&nbsp;Hua An ,&nbsp;Max Joshua Hülsey","doi":"10.1016/j.jcat.2025.116293","DOIUrl":"10.1016/j.jcat.2025.116293","url":null,"abstract":"<div><div>Numerous studies have demonstrated the potential of controlled periodic illumination in improving the quantum efficiency of heterogeneous photocatalytic reactions. However, the nature of the enhancement effect remains debated. Here, we report the promotion in photocatalytic activity of HCOOH-mediated 4-nitrophenol hydrogenation over Pd/TiO₂ via periodic illumination. Periodic illumination at 12 Hz led to a non-monotonic relationship between 4-nitrophenol conversion as a function of duty cycle, with 2.4 times enhancement in aminophenol yield at 10 % duty cycle. However, the improvement in photocatalytic activity was progressively diminished with increasing duty cycles and eventually discontinued at duty cycles above 50 %. Further exploring the operating limits of the current setup, we observed a maximum enhancement in 4-nitrophenol hydrogenation activity of 3.4-fold equivalent to 40-fold increase in quantum yield. Evaluation of simultaneous H₂ evolution rates and the effects of pH on aminophenol yield suggest that reduced amount of H* on the Pd nanoparticles contributes to 4-nitrophenol adsorption. We hypothesize that this difference in surface population leads to a crossover between two different kinetically dominant reaction mechanisms. Substantiated by kinetic and Pd poisoning studies, high H* under static and periodic illumination at duty cycles above 50 % leads to a dominant ionic pathway. In contrast, periodic illumination at lower duty cycles favors 4-nitrophenol adsorption and subsequent H* addition.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116293"},"PeriodicalIF":6.5,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144337915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cu and Ga dual sites on Ce0.9Zr0.1O2 for CO2 hydrogenation to methanol","authors":"Xuan Lu ,&nbsp;Xènia Garcia ,&nbsp;Isabel Serrano ,&nbsp;Martí Biset-Peiró ,&nbsp;Jing Yu ,&nbsp;Junshan Li ,&nbsp;Jordi Arbiol ,&nbsp;Andreu Cabot ,&nbsp;Jordi Llorca","doi":"10.1016/j.jcat.2025.116295","DOIUrl":"10.1016/j.jcat.2025.116295","url":null,"abstract":"<div><div>Cu-based catalysts are highly attractive for CO₂ hydrogenation to methanol due to their efficiency, selectivity, and cost-effectiveness. To further accelerate methanol synthesis, dual-site activation mechanisms are particularly effective. In this direction, solid solutions serve as effective supports, enhancing methanol production through improved hydrogenation, though the exact nature of the active sites in CuGa-based solid solutions remains unclear. In this study, we examine the synergistic interactions between Ga and Cu nanoparticles/clusters deposited on Ce_0.9Zr_0.1O₂ for CO₂-to-methanol hydrogenation. Through <em>in situ</em> diffuse reflectance infrared Fourier transform spectroscopy and temperature-programmed (TPR/TPD), we analyze the nature of the active sites and elucidate the reaction pathway. The results demonstrate that CO₂ adsorption and activation are favored by the appropriate Cu/Ga ratio, while Ga sites, in addition to Cu, play a critical role in promoting H₂ dissociation under methanol synthesis conditions. Furthermore, the oxygen vacancies in the CuGa/Ce_0.9Zr_0.1O₂ catalyst play a crucial role in stabilizing the key *HCOO intermediate, facilitating its further hydrogenation to methanol via the formate pathway. This synergy between Ga and Cu optimizes both CO₂ activation and hydrogenation steps, emphasizing Ga as an active site alongside Cu and highlighting the catalyst’s potential for efficient methanol production from CO₂.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116295"},"PeriodicalIF":6.5,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144337918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the synergy of dual heteroatom dopants in quantum dots for boosting photocatalytic CO2 reduction","authors":"Jing Wang ,&nbsp;Chengcheng Zhang ,&nbsp;Huating Liu ,&nbsp;Xusheng Wang ,&nbsp;Songtao Zhang ,&nbsp;Jinhua Ye ,&nbsp;Li Shi","doi":"10.1016/j.jcat.2025.116294","DOIUrl":"10.1016/j.jcat.2025.116294","url":null,"abstract":"<div><div>Doping semiconductor quantum dots (QDs) with heteroatoms has emerged as a technologically important tool for tuning their electronic structure and improving their photocatalytic activities; however, the resulting systems still suffer from low efficiency towards photocatalytic CO₂ reduction. Herein, we report that co-doping CdS QDs with Se^2- and Ga³⁺ can boost the photocatalytic CO₂ reduction. The achieved CO evolution rate over Ga/Se co-doped CdS QDs is almost 20 times higher than that of pristine CdS QDs, and is also higher than some other reported QDs based photocatalysts for CO₂ photoreduction. The mechanism study uncovers that the co-doping of Se and Ga in CdS QDs can suppress the recombination of photogenerated electron–hole pairs and decrease the formation barrier of the key *COOH intermediate for promoting the CO₂ to CO conversion.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116294"},"PeriodicalIF":6.5,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334882","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photo-plasma relay catalysis for molecular oxygen activation","authors":"Dexin Jin,&nbsp;Changhua Wang,&nbsp;Shuang Liang,&nbsp;Yuanyuan Li,&nbsp;Yichun Liu,&nbsp;Xintong Zhang","doi":"10.1016/j.jcat.2025.116292","DOIUrl":"10.1016/j.jcat.2025.116292","url":null,"abstract":"<div><div>Clean energy driven molecular oxygen activation (MOA) is crucial for the advancement of green oxidation technology and sustainable chemistry. While photocatalysis and plasma catalysis have long been regarded as promising green means for MOA, it remains largely unexplored by which mechanism these two processes can be combined to surpass the capability of each individually for efficient MOA. In this study, we couple photocatalysis with solution plasma catalysis by using oxides suspensions as the mediator, and elucidate the specific relay mechanism of photo-plasma catalysis for MOA. Among the various oxides tested, TiO₂ with an anatase–rutile mixed composition performs the best for photocatalysis-solution plasma synergy, resulting in 11.3 times and 5.6 times higher rate of oxidative decomposition of bisphenol A than that of photocatalysis and plasma catalysis alone, respectively. The solution plasma in synergy with UV excitation boosts the yield of ·O₂^– on rutile TiO₂ and the conversion of ·O₂^– to ¹O₂ on anatase TiO₂, thereby promoting a relay MOA at the anatase–rutile interface. Our findings on the relay mechanism of MOA and the promotion of synergy by the heterojunction interface open new avenues for clean energy driven catalytic reaction with heterojunction materials.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116292"},"PeriodicalIF":6.5,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144335205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RhI supramolecular assembly framework enables recyclable and thermal-stable catalysts for alkene functionalization","authors":"Hu Fang ,&nbsp;Zuowei Sun ,&nbsp;Shaokun Tao ,&nbsp;Tianhua Cui ,&nbsp;Yanxin Jiang ,&nbsp;Qianhui Wu ,&nbsp;Fanding Zhou ,&nbsp;Xianwen Zhang ,&nbsp;Weichao Xue ,&nbsp;Chunchun Zhang ,&nbsp;Yuqiao Zhou ,&nbsp;Jiaqi Xu ,&nbsp;Ruixiang Li ,&nbsp;Haiyan Fu ,&nbsp;Hua Chen ,&nbsp;Xueli Zheng","doi":"10.1016/j.jcat.2025.116285","DOIUrl":"10.1016/j.jcat.2025.116285","url":null,"abstract":"<div><div>The design of carrier-free recyclable catalysts is a key objective yet challenging task in modern catalysis. Here, we present the self-assembly of a nitrogen and phosphine-containing ligand (L) with Rh^I precusor to form a supramolecular assembly framework, (Rh^I₂L₂)_n·X, as confirmed by NMR, ESI-MS and X-ray crystallographic analysis. This Rh^I supramolecular assembly framework can partially dissolve in solution at high temperatures and fully recover at room temperature, facilitated by π-π, C–H···π and electrostatic interactions, thereby adopting the merits of both homogeneous and heterogeneous catalysis. The inherent coordination mode of Rh^I₂L₂ enables this Rh^I supramolecular assembly framework to serve as an effective catalyst for promoting the hydroformylation and hydrosilylation of alkenes, with its practicality further demonstrated in a continuous-flow mini-plant, kilogram-scale hydroformylation of Fischtropsch C₈ alkene, affording a turnover number of 1.27 × 10⁵ over a 100-hour recycling period. <em>In-situ</em> high-pressure FTIR and DFT calculation elucidate the role of nitrogen and the dynamic evolution of catalytic resting state in the presence of syngas and alkene.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116285"},"PeriodicalIF":6.5,"publicationDate":"2025-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144334883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nickel-catalyzed amination of aryl halides: An exogenous ligand-free approach to primary arylamines using TMSN3","authors":"Jiawei Huang ,&nbsp;Xiaoman Li ,&nbsp;Zhigang Lei ,&nbsp;Liang Xu ,&nbsp;Shuai Liu","doi":"10.1016/j.jcat.2025.116284","DOIUrl":"10.1016/j.jcat.2025.116284","url":null,"abstract":"<div><div>Efficiently synthesizing primary amines continues to pose a significant challenge in the field of synthetic chemistry. This study reports a highly effective nickel-catalyzed amination of aryl halides using trimethylsilyl azide (TMSN₃) as the nitrogen source, facilitated by methoxytrimethylsilane (MeO₃SiH) under thermal conditions. Notably, this reaction proceeds without the need for an exogenous ligand and under mild conditions. Mechanistic investigations reveal that (MeO)₃SiH promotes the formation of Ni(I) species, which cycle through Ni(I)/Ni(III) intermediates, driving the amination process efficiently.</div></div>","PeriodicalId":346,"journal":{"name":"Journal of Catalysis","volume":"450 ","pages":"Article 116284"},"PeriodicalIF":6.5,"publicationDate":"2025-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144329353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}