PtCo on continuous‐phase graphene as PEM fuel cell catalyst

Abstract

Summary For the first time, graphene grown by chemical vapor deposition (CVD) process is utilized as catalyst support following transfer onto polymer electrolyte membrane (M) or gas diffusion layer (GDL) as continuous‐phase. Thus, agglomeration and stacking of graphene sheets due to van der Waals forces are minimized. The main purpose of this study is investigation of PtCo atomic ratio on continuous‐phase graphene for PEM fuel cell. Eight different ratios of Pt (IV) and Co (II) salts are reduced on CVD grown graphene (G) sheet at room temperature using sodium borohydride to obtain varying PtCo nanoparticle compositions. Electrode activity increases with increasing atomic ratio of PtCo up to 1:3 both on membrane and gas diffusion layer for anode with the highest power densities of 1085 mW cm−2 (1:3‐PtCo/G‐M) and 1630 m W cm−2 (1:3‐PtCo/G‐GDL). For cathode, on the other hand, the highest performances are obtained with 1:2 PtCo/G‐M (355 mW cm−2 at 0.5 V) and 1:1 PtCo/G‐GDL (515 mW cm−2 at 0.5 V) compositions. The results show that the enhanced electrocatalytic activity is obtained at critical atomic ratio of Pt and Co due to changes in Pt‐Pt distances, d‐electron vacancy and adsorption. Continuous‐phase of graphene causes mass transfer limitations at the cathode effecting water removal at high current densities.

Recent Advances in the Development of Nanocarbon-Based Electrocatalytic/Electrode Materials for Proton Exchange Membrane Fuel Cells: A Review

“…Although graphene nanosheets have advantages, they can negatively affect MEA functioning. Therefore, when CVD graphene is used as a catalyst support deposited on GDLs, mass transfer limitations are observed at low polarization voltages when the current density suddenly decreases [55]. The high graphene content in the catalyst caused agglomeration, which characterizes the inefficiency of using such a layer to periodically remove water generated at the cathode [56].…”

Microporous 3D-Structured Hierarchically Entangled Graphene-Supported Pt3Co Alloy Catalyst for PEMFC Application with Process-Friendly Features

“…The increased d-band vacancy in the Pt atoms leads to the increased ability to accept the 2p electron donation from O 2 , resulting in improved Pt surface adsorption . As a result, the binding energy of the Pt–O bond becomes stronger, while the O–O bond becomes weaker. , Therefore, the lattice reconstruction in the alloy structure provides preferable sites for oxygen adsorption, which significantly accelerates the ORR kinetics. , Among the Pt alloy systems with various transition metals (Fe, Co, and Ni), Pt–Co alloys have previously been recognized with their higher ORR activity. − Compared to the other compositions of the Pt–Co alloy structures, the Pt 3 Co stoichiometry is primarily suitable for the ORR. − The active site of Pt in the Pt 3 Co alloys experiences a significant amount of ligand and strain effects, which are known to suppress the adsorption energy of the O 2 reduction intermediate species, resulting in increased ORR kinetics. , Moreover, the distribution of the controlled size and uniformity of the alloyed Pt 3 Co nanoparticles over the conducting support would increase the overall ORR activity and durability under the operating conditions. , As noted earlier, the controlled particle size and distribution of a nanoalloy phase have advantages in increasing the ECSA of the catalysts . The alloy structures with sub-nanometer particle sizes are reported to be high-performing toward the ORR as per the recent studies .…”

Co‐N as a Promoter towards Modulation Surface Chemistry of PtCo Alloy on 2D Thin Layer Hierarchical Porous Nitrogen‐Carbon for the Efficient Oxygen Reduction Reaction

“…Among all the Pt‐based nano‐bimetallic materials, PtCo has been identified in numerous studies as the most active and stable ORR catalyst. Co resulting a decrease in the Pt−Pt bonds distances leading to reduced OH adsorption on Pt and increase ORR activity [12] . Zhu et.…”

“…Co resulting a decrease in the PtÀ Pt bonds distances leading to reduced OH adsorption on Pt and increase ORR activity. [12] Zhu et. al.…”