High Performance Palladium Supported on Nanoporous Carbon under Anhydrous Condition

Abstract

Due to the high cost of polymer electrolyte fuel cells (PEFCs), replacing platinum (Pt) with some inexpensive metal was carried out. Here, we deposited palladium nanoparticles (Pd-NPs) on nanoporous carbon (NC) after wrapping by poly[2,2′-(2,6-pyridine)-5,5′-bibenzimidazole] (PyPBI) doped with phosphoric acid (PA) and the Pd-NPs size was successfully controlled by varying the weight ratio between Pd precursor and carbon support doped with PA. The membrane electrode assembly (MEA) fabricated from the optimized electrocatalyst with 0.05 mgPd cm−2 for both anode and cathode sides showed a power density of 76 mW cm−2 under 120 °C without any humidification, which was comparable to the commercial CB/Pt, 89 mW cm−2 with 0.45 mgPt cm−2 loaded in both anode and cathode. Meanwhile, the power density of hybrid MEA with 0.45 mgPt cm−2 in cathode and 0.05 mgPd cm−2 in anode reached 188 mW cm−2. The high performance of the Pt-free electrocatalyst was attributed to the porous structure enhancing the gas diffusion and the PyPBI-PA facilitating the proton conductivity in catalyst layer. Meanwhile, the durability of Pd electrocatalyst was enhanced by coating with acidic polymer. The newly fabricated Pt-free electrocatalyst is extremely promising for reducing the cost in the high-temperature PEFCs.

Silver–Palladium Electrodeposition on Unsupported Vulcan XC-72R for Oxygen Reduction Reaction in Alkaline Media

“…In eq ), j k is the kinetic-limiting current density, j d is the limiting current density, n is the number of transferred electrons in the reaction, F is the Faraday constant (96485.34 C mol –1 ), k is the electron transfer rate constant, C o is the bulk concentration of O 2 in the electrolyte involved (1.2 mM L –1 ) 2 , D o is the diffusion coefficient of O 2 (2 × 10 –5 cm 2 s –1 ), , νis., kinematic viscosity of the electrolyte (1 × 10 –2 cm 2 s –1 ) 2 , and ω is angular velocity in rad/s (2π N , N being the linear rotation speed). ,, Koutecky–Levich plots are shown in Supporting Information Figures S4–S6, and the corresponding n – E dependencies are given in Figure S7. Most of the catalysts present linear relationships between the limiting current density and the rotation rate.…”

“…Recent studies have proposed electrocatalysts that can carry out more efficient reduction of oxygen to water. These include noble metals (e.g., Pd, Pt, and Au), alloys (e.g., Ag–Co, Ag–Cu, and Pt–Co), ,, iron-based catalysts (e.g., FePSe 3 ), carbon materials (e.g., carbon black and graphene), and quinone (e.g., the anthraquinone process), among others. , These electrocatalysts can be prepared in diverse ways depending on the purpose and materials needed. Several FC studies have reported the modification of the electrode surface with noble metal nanoparticles (NPs) such as Pt, Au, and Pd .…”

Palladium/Stannic Oxide Interfacial Chemistry Promotes Hydrogen Oxidation Reactions in Alkaline Medium

“…The most significant peak is PdO reduction (0.5-0.8 V vs. RHE), whose coulombic charges are integrated to determine the electrochemical active surface area (ECSA) of the electrocatalysts following the conventional method. [49] The ECSA values of 263.4 and 962.0 cm 2 mg À 1 are estimated for Pd/MOFDC and Pd/SnO 2 /MOFDC, respectively. The oxophilic and spill-over properties of Sn and SnO 2 were verified experimentally with cyclic voltammetry (CV), where the addition Sn@SnO 2 transfer more O species to the Pd electrocatalyst, thereby enhances the PdO reduction peak in the Pd/SnO 2 /MOFDC and requires lower energy than the Pd/MOFDC, as its potential is shifted lower values.…”