Nanoscale Design of Pd‐Based Electrocatalysts for Oxygen Reduction Reaction Enhancement in Alkaline Media

Abstract

Palladium (Pd)‐based electrocatalysts have recently emerged as one class of the foremost promising candidates for the oxygen reduction reaction (ORR) in alkaline media due to their excellent ORR activity and durability and lower costs compared with platinum. Insightful design of Pd‐based nano‐architectures with optimized active surface sites and maximal intrinsic performance is central to promoting the ORR applications. To further accelerate the sluggish ORR kinetics at the cathode of fuel cells and substantially decrease the overall cost of the electrocatalysts, various strategies, including controlled sizes and shapes with selected crystallographic facets, crystal‐phase engineering, heteroatom doping, tailored surface strains, and surface engineering by de‐alloying, have been extensively developed in the past decade. In this review, a brief introduction to the fundamental ORR mechanisms of Pd‐based electrocatalysts in alkaline media is presented, followed by a thorough discussion on various strategies for delicately designing high‐performance Pd‐based catalysts with corresponding examples. Thereafter, the perspectives and new insights into the challenges are outlined, and some emerging research directions related to the rational design and controlled synthesis of Pd‐based ORR electrocatalysts are also proposed.

Native Ligand Carbonization Renders Common Platinum Nanoparticles Highly Durable for Electrocatalytic Oxygen Reduction: Annealing Temperature Matters

“…As shown in Figure S11 (Supporting Information), thermal annealing of PtPd NPs (≈4 nm in diameter) supported on KB at 700 °C produced graphitic-shell-coated PtPd catalysts with an excellent ORR activity and stability (Table S1, Supporting Information). [59,60] Moreover, this ligand carbonization strategy can further be applied to improve the stability of commercial Pt/C catalysts. Surface modification was realized by mixing Pt/C catalysts (J&M, HISPEC3000, particle size ≈ 3 nm, Pt loading ≈ 20 wt%) with OAm ligands in isopropanol followed by stirring overnight.…”

“…As shown in Figure S11 (Supporting Information), thermal annealing of PtPd NPs (≈4 nm in diameter) supported on KB at 700 °C produced graphitic‐shell‐coated PtPd catalysts with an excellent ORR activity and stability (Table S1, Supporting Information). [ 59,60 ]…”

Noble Metal-Based Catalysts with Core-Shell Structure for Oxygen Reduction Reaction: Progress and Prospective

“…The metal with high redox potential is first reduced to form the core. Additionally, the metal with a low oxidation-reduction potential is reduced and deposited on the core to form the core–shell structure [ 66 ].…”

High C–C cleavage efficiencies of ethanol oxidation reaction on mesoporous RhPt electrocatalysts

“…In addition to the above-discussed composition regulation of an electrocatalyst, it is well known that its activity also depends to a large extent on its structure and morphology. [31][32][33] For example, hollow and porous nanostructures can offer higher electrocatalytic performance than solid nanoparticles, because the former provides more of abundant active sites, namely, bigger active surface areas and improved atomic utilization efficiency. In this context, hollow porous Rh nanoballs possessed enormous low-coordinated sites for the oxidation of CO, leading to promoted catalytic EOR performance.…”