Synergistic Combination of Pd and Co Catalyst Nanoparticles over Self-Designed MnO₂Structure: Green Synthetic Approach and Unprecedented Electrode Kinetics in Direct Ethanol Fuel Cell

Abstract

The present study deals with sonochemical synthetic approach in fabricating PdCo/MnO 2 catalyst for the study of ethanol oxidation reaction in alkali medium. SEM and TEM images reveal that MnO 2 morphology is changed from nanowire to nanorod during intercalation of Pd, Co NPs in the support materials. Charge transfer across the electrode− electrolyte interface becomes facile due to (2 × 2) pore tunnels of α MnO 2 . Lowering of Pd loading around 40% in the catalyst matrix by Co not only makes the catalyst cheaper but also enhances the ethanol oxidation current by 66.3% compared to Pd/C. Extensive electrolysis on Pd 61 Co 39 /MnO 2 over a considerable span of potential is reflected in the voltammetric features, typically demonstrating the synergistic effect of the Pd−Co ad atoms ingrained on α MnO 2 structure. Chrono-amperometric analysis for an extended period indicates excellent sustainability of Pd 61 Co 39 /MnO 2 in the oxidation environment. The yield of oxidation products on Pd 61 Co 39 /MnO 2 , derived from ion chromatography, further substantiates the considerable extent of the anodic reactions delivering acetate and carbonates, on average, twice that on Pd/MnO 2 and four to five times that on Pd/C. Finally, 43.88 mW cm −2 power density was achieved during performance testing of the DEFC using the binary catalyst formulation on the noncarbon support.

Highly Dispersed Palladium Nanoparticles on Carbon-Decorated Porous Nickel Electrode: An Effective Strategy to Boost Direct Ethanol Fuel Cell up to 202 mW cm–2

“…Figure compares the peak power densities among the present fuel cell (star symbol), the representative AEM DEFC ,,− ,,− (circle symbols), and the state-of-the-art PEM DEFC (square symbol). The corresponding operating parameters and structural design of the alkaline DEFC have been summarized in Table .…”

“…Direct liquid fuel cell (DLFC) that overcomes the limitation of Carnot efficiency has been regarded as one of the most ideal power sources in the future. − Currently, DLFC, particularly anion exchange membrane (AEM)-based DLFC, receives ever-increasing attention, − because of its overwhelming superiority compared with a proton-exchange membrane (PEM)-based DLFC: quicker electrochemical kinetics, lower cost, and weaker corrosion. − However, the large-scale application of alkaline AEM DLFCs still suffers from technical obstacles, typically high system cost and low performance. − Developing high-efficiency and low-cost electrocatalyst for both anode and cathode is essential to lower system cost. Additionally, the microstructure and fabrication method of electrodes associated with their transport resistance and electrochemical kinetics are critical to improving cell performance. − Conventionally, carbon material such as carbon paper (CP) and carbon cloth (CC) is used as electrode supporting substrate for AEM DLFCs. − These commercial carbon materials possess the merits of low cost and high electronic conductivity. , However, they do not promote the electrocatalytic activity for electrode reactions. , By contrast, the porous metal is very attractive due to three-dimensional network structure, high mechanical strength, and controllable porosity and permeability. − Previous investigation has indicated that electrocatalytic activity of fuel oxidation reaction (typically ethanol, borohydride) in alkaline media can be greatly promoted by introducing nickel. , Therefore, to boost the performance of alkaline AEM DLFCs, significant efforts have been devoted to the porous nickel-based electrodes. − …”

Featured Contributes of Pd–Co-Decorated MnO2 NPs toward ORR Kinetics in Low-Temperature Fuel Cells: Outstanding Electrocatalysis Eliminating Pt and Carbon from Electrodes

“…The catalyst−support combination was maintained at ∼40:60 wt % ratio for the carbon as well as MnO 2 support, as reported in our earlier studies. 19 Material Characterization. X-ray diffractograms of the electrocatalysts were recorded using a SEIFERT-2000 diffractometer operating with CuK α radiation (λ = 0.1540 nm) generated at 35 kV and 30 mA with a scan rate of 1°min −1 for 2θ values between 20°and 90°.…”

“…The performance of a fuel cell depends on the complete utilization of a catalyst, and this can be achieved when the support offers a high surface area providing strong metal–support interaction (SMSI), thus generating extensive anchoring sites for the reactant molecules. Datta et al have earlier reported electrocatalytic studies on EOR/ORR with rare metal–support combinations involving a metal–polymer composite support (MoO 3 –polypyrrole, N -vinyl carbazole–V 2 O 5 ) , and a transition-metal oxide (TMO) support (MnO 2 , Fe 2 O 3 ) , which have already established their potential functional behavior toward EOR as well as in some cases for ORR, and these hybrid materials can pave the pathway for further studies under SMSI in catalysis. In this respect, extensive studies on graphene, carbon nanotube (CNT), conducting polymers (polypyrrole, polyvinyl carbazole, and polyaniline), transition-metal oxides (Fe 2 O 3 , TiO 2 , WO 3 , and MoO 3 ) ,,, single and bimetallic carbide support materials (MoC, W 2 C, Co 6 Mo 6 C 2 , and GC–Fe 2 MoC), − and layered double hydroxides (Ni–Fe–LDH, and Co–Ni–LDH) , have also been reported to be fruitful attempts for application in fuel cell catalysis.…”

Bimetallic Face-Centered Cubic Pd–Ag Nano-dendritic Alloys Catalysts Boost Ethanol Electrooxidation

“…Recently, platinum catalysts have been regarded as the ideal electrocatalysts for fuel cells. − However, there are still some problems like poor durability, slow reaction kinetics, and low natural reserves, and these greatly limit its prospects and large-scale commercial application . To improve the catalytic performance of electrocatalysts, there is a great interest in the research of non-platinum electrocatalysts. − Palladium is one of the platinum group metals; as an anodic catalyst, it shows great potential in electrocatalysis because it possesses excellent catalytic activity and stability in aqueous electrolytes. − Also, the electron structure of Pd can be optimized by alloying with other elements like nickel, , copper, , bismuth, , and tin ,, to form Pd-based alloys.…”