Enhancing CO Tolerance in PEMFC Anodes via Thermal Oxidation Induced RuO2 Blocking Shell on a PtRu/C Catalyst.

CO poisoning in Pt-based anode catalysts significantly hampers the proton exchange membrane fuel cell (PEMFC) performance. Despite great advances in CO-tolerant catalysts, their effectiveness is often limited to fundamental three-electrode systems, which is inadequate for practical PEMFC applications. Herein, we present a straightforward thermal oxidation strategy for constructing a Ru oxide blocking layer on commercial PtRu/C through a one-step Ru-segregation-and-oxidation process. The resulting 0.7 nm thick Ru oxide layer effectively inhibits CO adsorption while maintaining hydrogen oxidation activity. PtRu@RuO2/C demonstrates exceptional CO tolerance, enduring 1% CO in rotating disk electrode tests, an ∼10-fold improvement compared to that of PtRu/C. Crucially, it retains high HOR activity and CO tolerance in PEMFC, with negligible polarization curve loss in the presence of 100 ppm CO. Notably, 85% HOR activity is retained after a 4 h stability test. This enhancement contributes to the Ru oxide layer decelerating CO adsorption kinetics, rather than promoting CO oxidation via the classic bifunctional mechanism.

Rationally Designed L12-Pt2RhFe Intermetallic Catalyst with High CO-Tolerance for Alkaline Methanol Electrooxidation.

It is a grand challenge to deep understanding of and precise control over functional sites for the rational design of highly efficient catalysts for methanol electrooxidation. Here, an L12-Pt2RhFe intermetallic catalyst with integrated functional components is demonstrated, which exhibits exceptional CO tolerance. The Pt2RhFe/C achieves a superior mass activity of 6.43 A mgPt -1, which is 2.23-fold and 3.53-fold higher than those of PtRu/C and Pt/C. Impressively, the Pt2RhFe/C exhibits a significant enhancement in durability owing to its high CO-tolerance and stability. Density functional theory calculations reveal that high performance of Pt2RhFe intermetallic catalyst arises from the synergistic effect: the strong OH binding energy (OHBE) at Fe sites induce stably adsorbed OH species and thus facilitate the dehydrogenation step of methanol via rapid hydrogen transfer, while moderate OHBE at Rh sites promote the formation of the transition state (Pt-CO···OH-Rh) with a low activation barrier for CO removal. This work provides new insights into the role of OH binding strength in the removal of CO species, which is beneficial for the rational design of highly efficient catalysts.

WO3 -Assisted Synergetic Effect Catalyzes Efficient and CO-Tolerant Hydrogen Oxidation for PEMFCs.

Developing anode catalysts with substantially enhanced activity for hydrogen oxidation reaction (HOR) and CO tolerance performance is of great importance for the commercial applications of proton exchange membrane fuel cells (PEMFCs). Herein, an excellent CO-tolerant catalyst (Pd-WO3 /C) has been fabricated by loading Pd nanoparticles on WO3 via an immersion-reduction route. A remarkably high power density of 1.33 W cm-2 at 80 °C is obtained by using the optimized 3Pd-WO3 /C as the anode catalyst of PEMFCs, and the moderately reduced power density (73% remained) in CO/H2 mixed gas can quickly recover after removal of CO-contamination from hydrogen fuel, which is not possible by using Pt/C or Pd/C as anode catalyst. The prominent HOR activity of 3Pd-WO3 /C is attributed to the optimized interfacial electron interaction, in which the activated H* adsorbed on Pd species can be effectively transferred to WO3 species through hydrogen spillover effect and then oxidized through the H species insert/output effect during the formation of Hx WO3 in acid electrolyte. More importantly, a novel synergetic catalytic mechanism about excellent CO tolerance is proposed, in which Pd and WO3 respectively absorbs/activates CO and H2 O, thus achieving the CO electrooxidation and re-exposure of Pd active sites for CO-tolerant HOR.

Dual tolerance of ageratum (Ageratum conyzoides L.) to combined pollution of acid and cadmium: Field survey and pot experiment.

A field survey and pot experiment were carried out to screen tolerant plants growing in cadmium (Cd)-polluted mining areas which were co-polluted with acid in soil, and the related physiological and biochemical mechanisms were also analyzed. Thirty-seven species of wild plants and their corresponding soil were collected from a farmland around the mining areas. Ageratum (Ageratum conyzoides L.) with strong Cd-accumulative ability was selected, and its tolerance experiment for acid and Cd with different levels were carried out separately or orthogonally, respectively. Furthermore, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and the contents of malondialdehyde (MDA), photosynthetic pigments, soluble sugar and proline in its leaves were determined. The results showed that the Cd accumulation in ageratum and sticktight (Bidens pilosa L.) was relatively high, but the latter has been well documented, so we focused on ageratum in the present work. In pot experiment, ageratum grew normally at 100 mg kg-1 Cd in soil, and the Cd concentrations in its roots, stems and leaves were 75.37 ± 7.37, 31.01 ± 3.76 and 53.92 ± 10.05 mg kg-1, respectively. In the case of acid tolerance experiment, all plant individuals of ageratum grew normally when soil pH was over 3.5. In the orthogonal experiment, the Cd accumulation in this plant increased with the decrease of soil pH under the same Cd treatment. Under strong acid conditions, the activity of SOD in leaves of ageratum was increased significantly. When the Cd concentration was 10 mg kg-1 and the soil pH was 5.5 or 3.5, the activities of POD and CAT were significantly increased. In addition, based on stepwise regression analysis, the leaf Cd concentration was significantly positive correlated with the activities of SOD and POD in leaves of ageratum. Therefore, ageratum not only had a strong tolerance for Cd and acid pollution in soil, but also had a strong ability to accumulate Cd. As a common plant in the mining area, it has a great potential for the phytoremediation of Cd and acid co-contaminated soil.

Pb-Modified Ultrathin RuCu Nanoflowers for Active, Stable, and CO-resistant Alkaline Electrocatalytic Hydrogen Oxidation.

CO poisoning of Pt group metal (PGM) catalysts is a chronic problem for hydrogen oxidation reaction (HOR), the anodic reaction of hydroxide exchange membrane fuel cell (HEMFC) for converting H2 to electric energy in sustainable manner. We demonstrate here an ultrathin Ru-based nanoflower modified with Pb (PbRuCu NF) as an active, stable, and CO-resistant catalyst for alkaline HOR. Mechanism studies show that the presence of Pb can weaken the adsorption of *H, strengthen *OH adsorption to facilitate CO oxidation, as a result of significantly enhanced HOR activity and improved CO tolerance. Furthermore, in situ electrochemical attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) suggests that Pb acts as oxygen-rich site to regulate the behavior of the linear CO adsorption. The optimized Pb1.04 -Ru92 Cu8 /C displays a mass activity and specific activity of 1.10 A mgRu -1 and 5.55 mA cm-2 , which are ≈10 and ≈31 times higher than those of commercial Pt/C. This work provides a facile strategy for the design of Ru-based catalyst with high activity and strong CO-resistance for alkaline HOR, which may promote the fundamental researches on the rational design of functional catalysts.

Suppressing Electron Back-Donation for a Highly CO-tolerant Fuel Cell Anode Catalyst via Cobalt Modulation.

Platinum on carbon (Pt/C) catalyst is commercially adopted in fuel cells but it undergoes formidable active-site poisoning by carbon monoxide (CO). In particular, given the sluggish kinetics of hydrogen oxidation reaction (HOR) in anion-exchange membrane fuel cell (AEMFC), the issues of Pt poisoning and slow rate would combine mutually, notably worsening the device performances. Here we overcome these challenges through incorporating cobalt (Co) into molybdenum-nickel alloy (MoNi4 ), termed Co-MoNi4 , which not only shows superior HOR activity over the Pt/C catalyst in alkali, but more intriguingly exhibits excellent CO tolerance with only small activity decay after 10 000 cycles in the presence of 500 parts per million (ppm) CO. When feeding with CO (250 ppm)/H2 , the AEMFC assembled by this catalyst yields a peak power density of 394 mW cm-2 , far exceeding the Pt/C catalyst. Experimental and computational studies reveal that weakened CO chemisorption originates from the electron-deficient Ni sites after Co incorporation that suppresses d→CO 2π* back-donation.

Neighboring Pt Atom Sites in an Ultrathin FePt Nanosheet for the Efficient and Highly CO-Tolerant Oxygen Reduction Reaction.

Single atom catalyst and ultrathin two-dimensional (2D) nanostructures exhibit improved properties because of the improved exposure of more active atomic sites and optimized electronic structures. However, the oxygen reduction reaction (ORR) in fuel cells via a fast four-electron path usually uses at least two Pt atoms, which cannot be realized in highly isolated single Pt atoms. The synthesis of a densely dispersed single atom catalyst with adjacent atoms accessible at the same time on a matrix with a high surface area provides a feasible way and, however, is challenging. Here, we synthesize ultrathin FePt nanosheets (NSs) with 6.7 wt % neighboring dispersed Pt atoms. Different from the reported isolated Pt single atom catalysts, these ultrathin wrinkled FePt NSs with neighboring Pt sites adopt a four-electron reduction pathway, a high electrochemical active surface area (ECSA) of 545.54 m2 gPt-1, and an improved mass activity 7 times as high as Pt/C in the ORR. The improved performance results from the optimal use of neighboring Pt atoms dispersed in a more packed spacing and exposed on the surface of ultrathin sheets. The Pt atoms can interact synergistically to catalyze a fast ORR process. Furthermore, both the experiment and density functional theory (DFT) calculation indicated an outstanding CO-tolerance performance of this catalyst in the ORR.

A Molecular Cobalt Hydrogen Evolution Catalyst Showing High Activity and Outstanding Tolerance to CO and O2.

There is a demand to develop molecular catalysts promoting the hydrogen evolution reaction (HER) with a high catalytic rate and a high tolerance to various inhibitors, such as CO and O2 . Herein we report a cobalt catalyst with a penta-dentate macrocyclic ligand (1-Co), which exhibits a fast catalytic rate (TOF=2210 s-1 ) in aqueous pH 7.0 phosphate buffer solution, in which proton transfer from a dihydrogen phosphate anion (H2 PO4 - ) plays a key role in catalytic enhancement. The electrocatalyst exhibits a high tolerance to inhibitors, displaying over 90 % retention of its activity under either CO or air atmosphere. Its high tolerance to CO is concluded to arise from the kinetically labile character of undesirable CO-bound species due to the geometrical frustration posed by the ligand, which prevents an ideal trigonal bipyramid being established.

Transition-Metal Nitride Core@Noble-Metal Shell Nanoparticles as Highly CO Tolerant Catalysts.

Core-shell architectures offer an effective way to tune and enhance the properties of noble-metal catalysts. Herein, we demonstrate the synthesis of Pt shell on titanium tungsten nitride core nanoparticles (Pt/TiWN) by high temperature ammonia nitridation of a parent core-shell carbide material (Pt/TiWC). X-ray photoelectron spectroscopy revealed significant core-level shifts for Pt shells supported on TiWN cores, corresponding to increased stabilization of the Pt valence d-states. The modulation of the electronic structure of the Pt shell by the nitride core translated into enhanced CO tolerance during hydrogen electrooxidation in the presence of CO. The ability to control shell coverage and vary the heterometallic composition of the shell and nitride core opens up attractive opportunities to synthesize a broad range of new materials with tunable catalytic properties.

Displacement plating of a mesoporous Pt skin onto Co nanochains in a low-concentration surfactant solution.

Mesoporous Pt skins on Co nanochains are successfully synthesized by a displacement reaction between Pt species and a Co support with the assistance of surfactant micelles. The assembly of surfactant micelles on Co nanochains plays a key role in the formation of mesoporous Pt layers. The evolution of the mesoporous Pt layers is carefully studied at different time intervals. As the reaction time increases, the mesoporous Pt layers become thicker, and well-defined mesoporous structures gradually develop. The obtained mesoporous Pt skin exhibits high activity and superior CO tolerance in the electro-oxidation reaction of methanol. The mesoporous Pt skin also shows very high durability, and only a 20.2 % loss of the Pt electrochemical surface area is found even after a harsh durability test.

Influence of salinity on the thermal tolerance of aquatic organisms.

Aquatic organisms are challenged by changes in their external environment, such as temperature and salinity fluctuations. If these variables interacted with each other, the response of organisms to temperature changes would be modified by salinity and vice versa. We tested for potential interaction between temperature and salinity effects on freshwater, brackish, and marine organisms, including algae, macrophytes, heterotrophic protists, parasites, invertebrates, and fish. We performed a meta-analysis that compared the thermal tolerance (characterised by the temperature optimum, lower and upper temperature limits, and thermal breadth) at various salinities. The meta-analysis was based on 90 articles (algae: 15; heterotrophic protists: 1; invertebrates: 43; and fish: 31). Studies on macrophytes and parasites were lacking. We found that decreasing salinity significantly increased and decreased the lower and upper temperature limits, respectively, in all groups. Thus, a lowered salinity increased the thermal sensitivity of organisms. These findings mainly reflect the response of brackish and marine organisms to salinity changes, which dominated our database. The few studies on freshwater species showed that their lower thermal limits increased and the upper thermal limits decreased with increasing salinity, albeit statistically nonsignificant. Although non-significant, the response of thermal tolerance to salinity changes differed between various organism groups. It generally decreased in the order of: algae > invertebrates > fish. Overall, our findings indicate adverse effects of salinity changes on the temperature tolerance of aquatic organisms. For freshwater species, studies are comparatively scarce and further studies on their thermal performance at various salinity gradients are required to obtain more robust evidence for interactions between salinity and temperature tolerance. Considering test conditions such as acclimation temperature and potential infection with parasites in future studies may decrease the variability in the relationship between salinity and thermal tolerance.

Semimetal-triggered covalent interaction in Pt-based intermetallics for fuel-cell electrocatalysis.

Platinum-based intermetallic compounds (IMCs) play a vital role as electrocatalysts in a range of energy and environmental technologies, such as proton exchange membrane fuel cells. However, the synthesis of IMCs necessitates recombination of ordered Pt-M metallic bonds with high temperature driving, which is generally accompanied by side effects for catalysts' structure and performance. In this work, we highlight that semimetal atoms can trigger covalent interactions to break the synthesis-temperature limitation of platinum-based intermetallic compounds and benefit fuel-cell electrocatalysis. Attributed to partial fillings of p-block in semimetal elements, the strong covalent interaction of d-p π backbonding can benefit the recombination of ordered Pt-M metallic bonds (PtGe, PtSb and PtTe) in the synthesis process. Moreover, this covalent interaction in metallic states can further promote both electron transport and orbital fillings of active sites in fuel cells. The semimetal-Pt IMCs were obtained with a temperature 300 K lower than that needed for the synthesis of metal-Pt intermetallic compounds and reached the highest CO-tolerant oxygen reduction activity (0.794 A mg-1 at 0.9 V and 5.1% decay under CO poisoning) among reported electrocatalysts. We anticipate that semimetal-Pt IMCs will offer new insights for the rational design of advanced electrocatalysts for fuel cells.

Platinum-Tellurium Heterojunction Nanosheet Assemblies for Efficient Direct Formic Acid Electrooxidation Catalysis.

Two-dimensional (2D) heterojunction nanomaterials offer exceptional physicochemical and catalytic properties, thanks to their special spatial electronic structure. However, synthesizing morphologically uniform 2D platinum (Pt)-based metallic nanomaterials with diverse crystalline phases remains a formidable challenge. In this study, we have achieved the successful synthesis of advanced 2D platinum-tellurium heterojunction nanosheet assemblies (Ptx-PtTe2 HJNSAs, x = 0, 1, 2), seamlessly integrating both trigonal PtTe2 (t-PtTe2) and cubic Pt (c-Pt) phases. By enabling efficient electron transport and leveraging the specific electron density present at the heterojunction, the Pt2-PtTe2 HJNSAs/C demonstrated exceptional formic acid oxidation reaction (FAOR) activity and stability. Specifically, the specific and mass activities reached 8.4 mA cm-2 and 6.1 A mgPt-1, which are 46.7 and 50.8 times higher than those of commercial Pt/C, respectively. Impressively, aberration-corrected high-angle annular dark field scanning transmission electron microscopy (AC-HAADF-STEM) revealed a closely packed arrangement of atomic layers and a coherent intergrowth heterogeneous structure. Density functional theory (DFT) calculations further indicated that rearrangement of electronic structure occurred on the surface of Pt2-PtTe2 HJNSAs resulting in a more favorable dehydrogenation pathway and excellent CO tolerance, beneficial for performance improvement. This work inspires the targeted exploration of Pt-based nanomaterials through 2D heterostructure design, leading to an important impact on fuel cell catalysis and beyond.

A hybrid FeOx/CoOx/Pt ternary nanocatalyst for augmented catalysis of formic acid electro-oxidation.

Platinum-based catalysts that have long been used as the anodes for the formic acid electro-oxidation (FAO) in the direct formic acid fuel cells (DFAFCs) were susceptible to retrogradation in performance due to CO poisoning that impaired the technology transfer in industry. This work is designed to overcome this challenge by amending the Pt surface sequentially with nanosized cobalt (nano-CoOx, fibril texture of ca. 200 nm in particle size) and iron (nano-FeOx, nanorods of particle size and length of 80 and 253 nm, respectively) oxides. This enriched the Pt surface with oxygenated groups that boosted FAO and mitigated the CO poisoning. The unfilled d-orbitals of the transition metals and their tendency to vary their oxidations states presumed their participation in a faster mechanism of FAO. Engineering the Pt surface in this FeOx/CoOx/Pt hierarchy resulted in a remarkable activity toward FAO, that exceeded four times that of the Pt catalyst with up to ca. 2.5 times improvement in the catalytic tolerance against CO poisoning. This associated a ca. - 32 mV shift in the onset potential of FAO which increased to - 40 mV with a post-activation of the same catalyst at - 0.5  in 0.2 mol L-1 NaOH, displaying the catalyst's competitiveness in reducing overpotentials in DFAFCs. It also exhibited a favorable amelioration in the catalytic durability in long-termed chronoamperometric electrolysis. The electrochemical impedance spectroscopy and the CO stripping voltammetry were employed to elucidate the origin of enhancement.

Systematic DFT studies of CO-Tolerance and CO oxidation on Cu-doped Ni surfaces.

Nickel-based surfaces have received significant attention as an efficient substrate for electrooxidation. This work studied doped nickel surfaces with Cu atoms to enhance the CO-Tolerance. A comparative study was performed for CO adsorption upon different cleavage facets of pristine and Cu-doped nickel surfaces, whereas the adsorption energy, charge transfer, and density of state for CO were estimated using GGA-RPBE calculation method. Several adsorption probabilities were considered, and the change in adsorption energy and bond lengths were used to explain the CO adsorption mechanism. Otherwise, the density of state was employed to study the 3σ and 1π orbital to demonstrate the adsorption of CO onto the different facets. According to our analysis, the Cu-doped nickel surface showed higher CO tolerance than the pristine nickel surface. Whereas the calculated CO adsorption energies of Cu-doped surfaces have more positive values than the non-doped counterparts. The catalytic ability of pristine and Cu-doped Ni(111) was studied to evaluate the ability of surface poisoning resistance. Thus, oxidation of CO to CO2 was studied using the Eley-Rideal mechanism upon the pristine and Cu-doped surfaces of Ni(100) where the rate-determining step for CO oxidation upon the reported surfaces was estimated as CO + O2* → CO2* + O* by an energy barrier of 1.05 and 0.9 eV for pristine, and Cu-doped Ni (100).

Electro-oxidation Reaction of Methanol over Reducible Ce1-x-yNixSryO2-δ: A Mechanistic Probe of Participation of Lattice Oxygen.

Methanol oxidation reaction crucially depends on the formation of -OOH species over the catalyst's surface. Ni-based catalysts are by far the choice of materials, where the redox couple of Ni2+/Ni3+ facilitates the formation of -OOH species by surface reconstructions. However, it is challenging to oxidize Ni2+ as it generates charge-transfer orbitals near the Fermi energy level. One possible solution is to substitute Ni2+ with a reducible oxide support, which will not only facilitate the Ni2+ → Ni3+ oxidation but also adsorb oxygenated species like -OOH at a lower potential owing to its oxophilicity. This work shows with the help of structural and surface studies that the reducible CeO2 support in Ni and Sr co-doped Ce1-x-yNixSryO2-δ solid solution can easily facilitate Ni2+ → Ni3+ oxidation as well as evolution of lattice oxygen during the methanol oxidation reaction. While the Ni3+ species helped in formation of -OOH surface intermediates, the evolved lattice oxygen eased the CO oxidation process in order to bring out the better CO-tolerant methanol oxidation activity over Ce1-x-yNixSryO2-δ. The study shows the unique importance of the electronic interactions between the active site and support and involvement of lattice oxygen in the methanol oxidation reaction.

Nb12 +-niobespherene: a full-metal hollow-cage cluster with superatomic stability and resistance to CO attack.

Why one chemical is more stable than another is not always easy to understand. A unified answer for metal clusters has led to the establishment of the superatom concept, which rationalizes the delocalization of electrons; however, cluster stability based on superatom theory has not been confirmed unambiguously for any metal other than the s- and p-blocks of the periodic table of elements. Here, we have prepared pure niobium clusters and observed their reactions with CO under sufficient gas collision conditions. We find prominent inertness of Nb12 +, which survives CO attack. Comprehensive theoretical calculation results reveal that the inertness of Nb12 + is associated with its cage structure and well-organized superatomic orbitals, giving rise to energetic superiority among the studied clusters. It is revealed that not only the 5s but also the 4d electrons of Nb delocalize in the cluster and significantly contribute to the superatomic state, resulting in reasonable cage aromaticity. This hollow-cage cluster, which we have called a 'niobespherene', provides a clue with regard to designing new materials of all-metal aromaticity and Nb-involved catalysts free of CO poisoning.

Bismuth Incorporation in Palladium Hydride for the Electrocatalytic Ethanol Oxidation with Enhanced CO Tolerance.

Introducing nonmetal and oxophilic metal into palladium (Pd)-based catalysts is beneficial for boosting electrocatalysis, especially regarding the improvement of mass activity (MA) and CO tolerance. Herein, the stable bismuth-doped palladium hydride (Bi/PdH) networks have been successfully fabricated through a simple one-step method. The intercalation of interstitial H atoms expands the lattice of Pd, and the doping of oxophilic metal Bi restrains the adsorption of poisonous intermediates on the surface of Pd, thereby improving the activity and durability of the as-prepared catalysts in the ethanol oxidation reaction (EOR). The obtained Bi/PdH networks manifest a remarkable MA of 8.51 A·mgPd-1, which is 11.18 times higher than that of commercial Pd/C (0.76 A·mgPd-1). The CO-stripping analysis results indicate that Bi doping can significantly prohibit CO adsorption on the surface of the Bi/PdH networks. The density functional theory (DFT) calculations also reveal that Bi doping enhances the OH* adsorption on the catalyst surface and mitigates the interaction between Pd and CO* intermediates, providing deeper insights into the origin of the enhanced EOR activity and CO tolerance. This work describes an impactful path for producing high-performance and durable PdH-based nanocatalysts.

Pt Single Atoms on CrN Nanoparticles Deliver Outstanding Activity and CO Tolerance in the Hydrogen Oxidation Reaction.

The large-scale application of proton exchange membrane fuel cells is currently hampered by high cost of commercial Pt catalysts and their susceptibility to poisoning by CO impurities in H2 feed. In this context, the development of CO-tolerant electrocatalysts with high Pt atom utilization efficiency for hydrogen oxidation reaction (HOR) is of critical importance. Herein, Pt single atoms are successfully immobilized on chromium nitride nanoparticles by atomic layer deposition method, denoted as Pt SACs/CrN. Electrochemical tests establish Pt SACs/CrN to be a very efficient HOR catalyst, with a mass activity that is 5.7 times higher than commercial PtRu/C. Strikingly, the excellent performance of Pt SACs/CrN is maintained after introducing 1000 ppm of CO in H2 feed. The excellent CO-tolerance of Pt SACs/CrN is related to weaker CO adsorption on Pt single atoms. This work provides guidelines for the design and construction of active and CO-tolerant catalysts for HOR.

Alloying with Mn Enhances the Activity and Durability of the CoPt Catalyst toward the Methanol Oxidation Reaction.

To improve the catalytic performance and durability of Pt catalysts used for the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs), alloying of Pt with other transition metals such as Ru, Co, Ni, and Fe is considered an effective approach. Despite the significant progress made in the preparation of bimetallic alloys and their utilization for MOR, improving the activity and durability of the catalysts to make them commercially viable remains a stiff challenge. In this work, trimetallic Pt100-x(MnCo)x (16 < x < 41) catalysts were successfully synthesized via borohydride reduction followed by hydrothermal treatment at 150 °C. The electrocatalytic performance of the synthesized trimetallic Pt100-x(MnCo)x (16 < x < 41) catalysts toward MOR was studied using cyclic voltammetry and chronoamperometry. The results affirm that all Pt100-x(MnCo)x (16 < x < 41) alloys have superior MOR activity and durability as compared to bimetallic PtCo alloys and commercially available Pt/C (comm. Pt/C) catalysts. Among all the compositions studied, the Pt60Mn1.7Co38.3/C catalyst exhibited superior mass activity (1.3 and 1.9 times higher than those of Pt81Co19/C and comm. Pt/C, respectively) toward MOR. Furthermore, all the newly synthesized Pt100-x(MnCo)x/C (16 < x < 41) catalysts showed better CO tolerance when compared with comm. Pt/C. This improved performance of the Pt100-x(MnCo)x/C (16 < x < 41) catalyst can be attributed to the synergistic effect of Co and Mn on the Pt lattice.