Excellent Methanol Tolerance Research Articles

High performance biomass-derived catalysts for the oxygen reduction reaction with excellent methanol tolerance

The discovery of low cost and efficient catalytic materials for the oxygen reduction reaction (ORR) is of paramount importance for industrial-scale fuel cell manufacture. In this work, a convenient and straightforward approach was designed and applied to produce iron and nitrogen co-doped biomass carbon/graphene composite (Fe–N/CB-RGO) by using soybean dregs combined with graphene oxide (GO). The results show that the optimized Fe–N/CB-RGO (1) sample has high catalytic activity and stability for ORR, the onset potential of Fe–N/CB-RGO (1) is 0.02 V vs. Hg/HgO, which is merely 50 mV negative-shifted comparison with commercial Pt/C. The composition optimized Fe–N/CB-RGO (1) catalyst showed excellent methanol tolerance, with the presence of methanol surprisingly improving ORR performance. This unique catalytic performance of the Fe–N/CB-RGO (1) catalyst is attributed to electron transfer synergies arising from close interfacial contact between the biomass-derived carbon and graphene.

Atomically deviated Pd-Te nanoplates boost methanol-tolerant fuel cells.

The methanol crossover effect in direct methanol fuel cells (DMFCs) can severely reduce cathodic oxygen reduction reaction (ORR) performance and fuel efficiency. As a result, developing efficient catalysts with simultaneously high ORR activity and excellent antipoisoning methanol capability remains challenging. Here, we report a class of Pd-Te hexagonal nanoplates (HPs) with a Pd20Te7 phase that simultaneously overcome the activity and methanol-tolerant issues in alkaline DMFC. Because of the specific arrangement of Pd atoms deviated from typical hexagonal close-packing, Pd-Te HPs/C displays extraordinary methanol tolerance with high ORR performance compared with commercial Pt/C. DFT calculations reveal that the high performance of Pd-Te HPs can be attributed to the breakthrough of the linear relationship between OOH* and OH* adsorption, which leaves sufficient room to improve the ORR activity but suppresses the methanol oxidation reaction. The concurrent high ORR activity and excellent methanol tolerance endow Pd-Te HPs as practical electrocatalysts for DMFC and beyond.

Cobalt- and iron-coordinated graphitic carbon nitride on reduced graphene oxide: A nonprecious bimetallic M–Nx–C analogue electrocatalyst for efficient oxygen reduction reaction in acidic media

The electrocatalytic oxygen reduction reaction (ORR) in acidic media is quite strenuous. Although platinum (Pt)-based materials are considered state-of-the-art ORR catalysts, their high cost and poor durability greatly impede their extensive application in polymer electrolyte membrane fuel cells and direct methanol fuel cells. Here, we report a bimetallic M–Nx–C-class electrocatalyst comprising Co- and Fe-coordinated graphitic carbon nitride ((Co,Fe)–CN) and reduced graphene oxide (RGO) as an effective substitute for expensive Pt-based catalysts for the ORR in acidic media. The fabricated (Co,Fe)–CN/RGO catalyst exhibits a high surface area, high porosity, fast charge-transfer kinetics at the (Co,Fe)–CN/RGO 2D/2D interface, and abundant Co–Nx–C and Fe–Nx–C active sites. Because of these favorable properties, the optimized (Co,Fe)–CN/RGO catalyst displayed extraordinary electrocatalytic ORR activity, with an onset potential of 875 mV, which is only 41 mV more negative than that of a commercial Pt/C, and follows an efficient four-electron reaction pathway in acidic media. Notably, the fabricated catalyst demonstrated excellent methanol tolerance and long-term stability compared with the reference Pt/C. Therefore, this work provides a rational design approach to fabricating graphitic-C3N4-based nonprecious bimetallic electrocatalysts with M–Nx–C active sites for enhanced ORR activity in fuel-cell applications.

Controllable preparation and synergistically improved catalytic performance of TiC/C hybrid nanofibers via electrospinning for the oxygen reduction reaction

Alkaline fuel cells are considered as promising energy conversion devices for future application, and oxygen reduction reaction (ORR) catalyst is one of the critical factors in determining fuel cells' performance. However, the application of conventional Pt-based catalysts is limited by its high cost and insufficient reserve. Here we synthesized TiC/C nanofibers as ORR catalyst through electrospinning. The morphology, TiC content, and interface between TiC and carbon in TiC/C nanofibers could be adjusted by changing preparation conditions. The changes in material properties affect the catalytic performance due to the synergistic enhanced effect between TiC and carbon. The best TiC/C sample (TCNFs/C) exhibited the ORR performance with the onset potential, peak potential, peak current density, and charge transfer number of 0.941 V vs. RHE, 0.812 V vs. RHE, 0.742 mA cm−2, and 3.29, respectively, as well as good catalytic durability and excellent methanol tolerance. The results demonstrate the great research value and application potential of TiC/C nanofibers as ORR catalysts.

Zinc, sulfur and nitrogen co-doped carbon from sodium chloride/zinc chloride-assisted pyrolysis of thiourea/sucrose for highly efficient oxygen reduction reaction in both acidic and alkaline media

Zn and N co-doped carbon (Zn-N-C) shows encouraging catalytic stability for oxygen reduction reaction (ORR) because of the fulfilled d orbital of Zn, but its catalytic activity is not satisfactory. Herein, hierarchically porous Zn, S and N co-doped carbon (Zn-S-N-C) with large specific surface area (2433 m2 g−1) and pore volume (3.007 cm3 g−1) is synthesized by using NaCl/ZnCl2-assisted pyrolysis of sucrose and thiourea. The Zn-S-N-C catalyst exhibits superior ORR activity with half-wave potentials (E1/2) up to 0.774 V in 0.1 M HClO4 and 0.894 V in 0.1 M KOH, good ORR stability with 19- and 4-mV loss in E1/2 values after 10,000 potential cycles in 0.1 M HClO4 and 0.1 M KOH, respectively, and excellent methanol tolerance. The good ORR performance of Zn-S-N-C can be attributed to its enhanced intrinsic ORR activity resulting from the formation of S, N doped carbon and ZnS in Zn-S-N-C, its hierarchically porous structure resulting from the pore-forming roles played by ZnCl2, NaCl and thiourea, and its improved graphitization degree resulting from the added ZnCl2 during Zn-S-N-C synthesis. This work will provide a novel strategy for the synthesis of hierarchically porous Zn, S and N co-doped carbon materials for ORR.

Silver sulfide nanoparticles incorporated into graphene oxide: an efficient electrocatalyst for the oxygen reduction reaction

We report a facile one-step sonochemical synthesis of silver sulfide incorporated into reduced graphene oxide (Ag2S-RGO) for the oxygen reduction reaction (ORR). The Ag2S-RGO nanocomposite was characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy with mapping, and X-ray photoelectron spectroscopy (XPS). To evaluate the electrochemical performance, the surface of a glassy carbon electrode (GCE) was modified with the Ag2S-RGO nanocomposite for the ORR. The Ag2S-RGO nanocomposite-modified GCE showed higher electrocatalytic performance toward the ORR in terms of the electrocatalytic current density and the shift in overpotential when compared with those of RGO and a commercial Pt/C catalyst. The maximum current density was found to be 0.554 mA cm−2 with an overpotential of − 0.39 V. Additionally, the proposed material showed excellent methanol tolerance, high stability, and good reproducibility and selectivity toward the reduction of O2.

Amino-metalloporphyrin polymers derived Fe single atom catalysts for highly efficient oxygen reduction reaction

Recently, nitrogen-doped porous carbon supported single atom catalysts (SACs) have become one of the most promising alternatives to precious metal catalysts in oxygen reduction reaction (ORR) due to their outstanding performance, especially those derived from porphyrin-based materials. However, most of them involve other metal residuals, which would cause the tedious pre- and/or post-treatment, even mislead the mechanistic investigations and active-site identification. Herein, we report a precursor-dilution strategy to synthesize Fe SACs through the Schiff-based reaction via co-polycondensation of amino-metalloporphyrin, followed by pyrolysis at high temperature. Systematic characterization results provide the compelling evidence of the dominant presence of atomically dispersed Fe-N x species. Our catalyst shows superior ORR performance with positive half-wave potential ( E 1/2= 0.85 V vs. RHE) in alkaline condition and moderate activity ( E 1/2= 0.68 V vs. RHE) under the acidic condition, excellent methanol tolerance and good long-term stability. All the results indicate Fe SACs would be a promising candidate for replacing the precious Pt in metal-air batteries and fuel cells.

Melamine‐Induced N,S‐Codoped Hierarchically Porous Carbon Nanosheets for Enhanced Electrocatalytic Oxygen Reduction

AbstractExploring an efficient strategy to enhance the catalytic oxygen reduction performance of carbon‐based catalysts is of great significance in the field of electrocatalysis. In this work, through a facile polymerization‐carbonization approach under the regulation of melamine, N,S‐codoped hierarchically porous carbon nanosheets with controllable morphology are fabricated by using polyaniline as the precursor. The resultant catalysts have favorable features of the synergetic effect of N,S co‐doping and the advanced structural property with high specific surface area and hierarchical pore structure, contributing to an encouraging onset potential (Eonset = 0.94 V) in alkaline media, comparable to that of Pt/C catalysts, as well as excellent electrochemical stability and methanol tolerance. By rationally adjusting the experimental parameters, the mechanism of melamine on the formation of final porous nanosheet structure during high‐temperature pyrolysis is clarified, and the optimal experimental conditions for the superior catalysts are also discussed. Furthermore, a rechargeable Zn‐air battery constructed with the resulting materials exhibits desirable performance with low charge‐discharge gap and impressive life‐span. This contribution would supply some novel inspiration to design carbon‐based materials with desired features for energy‐related technologies.

MOF/TBOT-derived hierarchical C-N/Co/Ti composites with effective elemental separation for enhanced oxygen reduction reaction

C-N/Co/Ti composites derived from ZIF-67@TiO2 precursors have been fabricated by a facile thermal treatment process. The morphology and composition are highly dependent on the available parameters inferring of exact hydrolysis of tetrabutyl titanate and sintering temperature. The obtained hierarchical microstructure is composed of numerous dodecahedron-like hollow boxes decorated with in-situ growth of size-tunable and twisting nanotubes on surfaces. The effective elemental separation of Ti and Co on the upper and lower ends of nanotubes can be realized by regulating the ionic migration and crystalline phase formation process at a high temperature. The as-prepared C-N/Co/Ti composites exhibit the enhanced electrocatalytic activities to oxygen reduction reaction (ORR) via a favorable four-electron pathway and the desired reaction kinetics with the low Tafel slope (67.8 mV dec−1), as well as the excellent methanol tolerance in comparison with the Pt/C electrocatalysts. The superior ORR electrocatalytic performance would be mainly contributed to the combination of the designed multi-phase composition, the enhanced surface adsorption/desorption, the modified surface/interface electron transfer mechanism, and the constructed Co/Ti double-active sites on different locations of microstructure. The present work presents a new insight for the synthesis of C-N-based inorganic composite with outstanding electrocatalytic behavior for ORR process.

Graphitizing N-doped mesoporous carbon nanospheres via facile single atom iron growth for highly efficient oxygen reduction reaction

Single atom catalyst is of great importance for the oxygen reduction reaction (ORR). However, facile preparation of single atom catalyst without using well-designed precursors or labor-intensive acid leaching remains an urgent challenge. Herein, a simple pyrolysis of Fe3+-loaded mesoporous phenolic resin (mPF)-melamine precursor is used to prepare the single atom iron-anchored N-doped mesoporous graphitic carbon nanospheres (Fe/N-MGN). Investigation of the synthesis reveals the appropriate Fe-assisted catalysis effect and mPF template effect, which not only spurs the highly graphitic porous framework of Fe/N-MGN with plentiful pyridinic N/graphitic N, but also assures the dispersed single atom Fe anchoring without elaborated procedures. As a result, the as-synthesized Fe/N-MGN demonstrates high catalytic activity, good durability and excellent methanol tolerance for ORR. This work promises a facile method to regulate the graphitic carbon growth and single atom Fe loading for the highly efficient electrocatalysis.

Fe/N-doped mesoporous carbons derived from soybeans: A highly efficient and low-cost non-precious metal catalyst for ORR

Oxygen reduction reaction (ORR) plays a crucial role in many energy storage and conversion devices. Currently, the development of inexpensive and high-performance carbon-based non-precious-metal ORR catalysts in alkaline media still gains a wide attention. In this paper, the mesoporous Fe-N/C catalysts were synthesized through SiO2-mediated templating method using biomass soybeans as the nitrogen and carbon sources. The SiO2 templates create a simultaneous optimization of both the surface functionalities and porous structures of Fe-N/C catalysts. Detailed investigations indicate that the Fe-N/C3 catalyst prepared with the mass ratio of SiO2 to soybean being 3:4 exhibits brilliant electrocatalytic performance, excellent long-term stability and methanol tolerance for the ORR, with the onset potential and the half-wave potential of the ORR being about 0.890 V and 0.783 V (vs RHE), respectively. Meanwhile, the desired 4-electron transfer pathway of the ORR on the catalysts can be observed. It is significantly proposed that the high BET specific surface area and the appropriate pore-size, as well as the high pyridinic-N and total nitrogen loadings may play key roles in enhancing the ORR performance for the Fe-N/C3 catalyst. These results suggest a feasible route based on the economical and sustainable soybean biomass to develop inexpensive and highly efficient non-precious metal electrochemical catalysts for the ORR.

PBA@PPy derived N-doped mesoporous carbon nanocages embedded with FeCo alloy nanoparticles for enhanced performance of oxygen reduction reaction

Due to the obstacle of sluggish kinetics on cathode of fuel cells and metal–air batteries, developing low-cost and durable electrocatalysts to replace the platinum-based catalysts still remains a grand challenge. Here, we describe a simple self-template approach to synthesize N-doped mesoporous carbon nanocages (FeCo@NC) embedded with FeCo alloy nanoparticles as oxygen reduction reaction (ORR) electrocatalyst. The resulting heterostructure is derived from corresponding PBA@PPy composites, which are pre-prepared by polymerization of polypyrrole (PPy) layer on Prussian blue analogue (PBA) nanocubes. The FeCo alloy nanoparticles with an average particle size of ∼10 nm are well dispersed and confined within the shell of carbon nanocages. Benefiting from the mesoporous structure and the synergetic interaction of binary metals, the optimized FeCo@NC-3-800 electrocatalyst exhibits comparable ORR performances (0.83 V for half-wave potential (E1/2), 5.323 mA cm−2 for limiting current density (Jk)), superior durability and excellent methanol tolerance to the commercial Pt/C (20 wt%). This work provides an appropriate strategy for general, efficient and practical synthesis of more promising non-precious metal electrocatalyst with high ORR activity.

Design and facile one-pot synthesis of uniform PdAg cubic nanocages as efficient electrocatalyst for the oxygen reduction reaction

Shape-controlled synthesis of multicomponent metallic nano-alloy materials is of great significance for the design and preparation of high-efficiency electrocatalysts. In this work, a simplified one-pot synthetic strategy for the preparation of uniform three-dimensional (3D) PdAg cubic nanocages (PdAg–CNC) was developed. The morphology and structure of PdAg–CNC were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). We elucidate a series of reaction pathways for the formation of various morphologies (sphere, cubic nanocage and nanowire) of PdAg alloys by tuning the amount of glycine and controlling the Pd/Ag molar ratio. The PdAg–CNC shows enhanced electrocatalytic activity, good durability and excellent methanol tolerance in comparison with commercial Pd–C and Pt–C catalysts for the oxygen reduction reaction (ORR) in alkaline medium. The excellent ORR performance of the PdAg–CNC can be correlated to the Pd–Ag alloy formation and unique mesoporous nanocage structure. This work demonstrates a facile strategy for shape-controlled synthesis of multicomponent metallic nano-alloys materials and their catalytic application.

Bamboo-like nitrogen-doped porous carbon nanofibers encapsulated nickel-cobalt alloy nanoparticles composite material derived from the electrospun fiber of a bimetal-organic framework as efficient bifunctional oxygen electrocatalysts.

The development of low-cost bifunctional electrocatalysts with both a high activity and long durability is critical for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The reasonable design and construction of bifunctional electrocatalysts is the key to energy storage and energy conversion technologies. In this study, transition metal carbon nitrides were used as a substitute for the precious metal catalyst, the Ni-Co-BTC (metal organic framework (MOF)) mixed with polyacrylonitrile (PAN) using electrostatic spinning technology to prepare the bamboo-like nanofibers precursor (Ni-Co-BTC@PAN). A series of electrocatalytic materials (NiCo-X@N-CNFs-Ts, T = 700, 800, 900 °C) were synthesized with nitrogen-doped carbon nanofibers coated with NiCo alloy nanoparticles using high temperature carbonization at different temperatures. We studied the effects of different calcination temperatures and different Ni/Co molar ratios of NiCo-X@N-CNFs-Ts (T = 700, 800, 900 °C) on the bifunctional catalytic performance of the ORR/OER. The composite, NiCo-0.8@N-CNFs-800, exhibited a highly doped-N level, uniform NiCo alloy nanoparticle dispersion and decentralized NiCo-Nx active sites, therefore affording an excellent bifunctional electrocatalytic performance. The ORR onset potential on NiCo-0.8@N-CNFs-800 was 0.91 V and the half-wave potential (E1/2) was 0.82 V, the NiCo-0.8@N-CNFs-800 corresponded to the minimum potential of 1.61 V at the current density of 10 mA cm-2 among all of the NiCo-X@N-CNFs-Ts hybrids under the OER condition. The NiCo-0.8@N-CNFs-800 catalyst exhibited a low reversible overpotential of 0.79 V between the ORR (E1/2) and OER (Ej = 10 mA cm-2) with excellent stability, durability and methanol tolerance, even surprisingly superior to the commercial Pt/C and RuO2 catalysts. This work provides a general strategy and useful guidance for the design and development of a variety of multifunctional non-noble metal catalysts for energy applications.

Enhancing the oxygen reduction reaction with three-dimensional graphene hollow nanosphere supported single-atomic cobalt catalyst

Three-dimensional graphene hollow nanospheres supported single-atomic cobalt catalyst shows superior electrocatalytic activity, long-term stability, and excellent methanol tolerance for the oxygen reduction reaction in alkaline media.

Highly active Fe-N-doped porous hollow carbon nanospheres as oxygen reduction electrocatalysts in both acidic and alkaline media.

Hierarchical iron-nitrogen-codoped porous hollow carbon spheres have been synthesized by using melamine-formaldehyde (MF) resin spheres as templates, nitrogen sources and pore-forming agents. FeCl3, 1,10-phenanthroline and carbon black were used as iron, nitrogen and carbon sources. The as-obtained porous hollow carbon spheres possess a high specific surface area of 807 m2 g-1, as well as exhibited excellent electrocatalytic activity for the oxygen reduction reaction (ORR) in both acidic and alkaline media. In 0.1 M HClO4 solution, the onset potential was 0.857 V (vs. RHE) and the half-wave potential was 0.715 V, which are only 78 and 80 mV less than those of the 20% Pt/C catalyst, respectively. In addition, in 0.1 M KOH solution, the onset potential was 1.017 V and the half-wave potential was 0.871 V for the ORR, which are 22 and 28 mV more positive than those of the Pt/C catalyst, respectively. Meanwhile, the catalyst also exhibited excellent methanol tolerance and long-term durability with a more effective four-electron pathway compared to the 20% Pt/C catalyst in both acidic and alkaline media. When used as an air-cathode catalyst for a Zn-air battery, the maximum power density of a Zn-air battery with the MF-C-Fe-Phen-800 cathode was 235 mW cm-2 at a high current density of 371 mA cm-2, and a high open-circuit potential of 1.654 V, superior to that of Pt/C (199 mW cm-2, 300 mA cm-2, 1.457 V). A series of designed experiments suggested that the remarkable performance was attributed to the high specific area, hollow carbon spheres, unique hierarchical micro-mesoporous structures, high contents of pyridinic-N and graphitic-N. The superiority of the as-prepared catalyst makes it promising for use in practical applications.

Optimization of Catalytic Sites in Cobalt‐Modified Nitrogen‐Doped Carbon towards High‐Performance Oxygen Reduction Electrocatalysts for Zinc‐Air Batteries

AbstractEfficient yet low‐cost electrocatalysts for the oxygen reduction reaction (ORR) are highly desirable for energy systems such as metal‐air batteries and fuel cells. Herein, we report the synthesis of efficient cobalt‐modified nitrogen‐doped carbon (N−C/Co) electrocatalysts by using a one‐pot pyrolysis. The abundant source of N in g‐C3N4 contributes to the in situ N doping in the carbon matrix, which favors the formation of Co‐related catalytic active sites. The N−C/Co‐1 (prepared with 1 mmol Co salt) sample exhibits the best performance towards the ORR, with a positive half‐wave potential of 0.86 V (vs. the reversible hydrogen electrode, RHE), high stability and excellent methanol tolerance, which outperforms the commercial Pt/C catalyst. We find that the high performance is dependent on the optimal content of Co that can achieve the maximum amount of Co−Nx catalytic species. In addition, we reveal that the size effect of Co nanoparticles is not the determining factor for the ORR activity in the current system, as the kinetics of the ORR reaction is dominantly determined by the active sites derived from Co−Nx species. By exploiting the N−C/Co‐1 sample as an air cathode catalyst, the assembled Zn‐air battery presents a maximal power density of 153 mW cm−2 as well as good durability during continuous cycle tests.

A One‐Pot Method to Synthesize a Co‐Based Graphene‐Like Structure Doped Carbon Material for the Oxygen Reduction Reaction

AbstractThe performance of the oxygen reduction reaction (ORR) is a core issue in of fuel cells. ORR is a slow kinetic process; platinum normally is used to accelerate the reaction. This is a bottleneck for further development of fuel cells. Transition metal and heteroatom co‐doped carbon materials have great potential in ORR catalysis. However, one‐step synthesis of high activity and stability transition metal and heteroatom co‐doped electrocatalysts is still a challenge. In this work, nitrogen, fluorine, and cobalt co‐doped carbon catalyst, MPCo‐950‐5, is prepared from melamine, polytetrafluoroethylene, and cobalt acetate by a one‐step method. MPCo‐950‐5 with a graphene‐like structure and its specific surface area is 642 m2 g−1. The ORR half‐wave potential of MPCo‐950‐5 is positively shifted by 35 mV compared to that of commercial Pt/C. In addition, MPCo‐950‐5 also shows excellent stability and methanol tolerance. This work serves as a simple and feasible method for preparing high ORR active transition metal and heteroatom co‐doped carbon materials.

Fe, N-decorated three dimension porous carbonaceous matrix for highly efficient oxygen reduction reaction

Rational engineering of simple, economical and durable nonprecious metal electrocatalyst with excellent oxygen reduction reaction (ORR) activity is crucial for the electrochemical energy conversion devices, such as metal-air batteries and fuel cells. Here, we developed a highly efficient ORR electrocatalyst with rich and well-dispersed Fe-Nx active sites and iron nanocrystals decorated three dimension (3D) porous carbonaceous matrix by a rational designed carbonaceous spheres templated strategy. The fabricated electrocatalyst exhibits outstanding ORR activity with onset potential of 1.0 V and half-wave potential of 0.90 V versus reversible hydrogen electrode in alkaline media, which is much better than benchmark Pt/C. In addition, it presents particularly better performance in terms of superior stability and excellent methanol tolerance capacity. Experimental studies display that the remarkable ORR activity primarily originates from the synergetic effect of rich Fe-Nx active sites, sufficient carbon encapsulated metallic iron nanocrystals and desired meso/microporous structure. What worth to point out is that the facile synthetic technique can be extended to fabricate other low cost highly active transition metal-N-carbon scaffolds ORR electrocatalysts.

Biodiesel Production Catalyzed by a Methanol-Tolerant Lipase A from Candida antarctica in the Presence of Excess Water.

In this article, biodiesel was prepared using a novel free liquid lipase A from Candida antarctica (CALA) as a catalyst in the presence of excess water. The methanol tolerance of CALA was investigated. The effect of reaction conditions, including the molar ratio of soybean oil to methanol, water load, CALA load, reaction temperature, and reaction time, was evaluated. Reaction thermodynamics and kinetics were also analyzed. Results showed that free liquid lipase CALA showed excellent methanol tolerance in the reaction system using one-step addition of methanol and can be used to prepare biodiesel with water load of 12–14%. The influence of three transesterification variables on biodiesel yield was water load > temperature > time. The transesterification conditions were optimized by response surface methodology as follows: CALA load 5%, substrate molar ratio (soybean oil/methanol) 1:7, water load 14%, reaction time 26 h, and temperature 38 °C. The maximum biodiesel yield (92.4 ± 0.8%) was obtained under optimal conditions. The activation energy for biodiesel formation was 52.58 kJ/mol. Kinetic parameters Km′ and Vmax were 4.84 × 10–1 mol/L and 6.85 × 10–2 mol/(L·min), respectively. The mechanism of CALA-catalyzed transesterification was also proposed.