A Comparison of “Bottom-Up” and “Top-Down” Approaches to the Synthesis of Pt/C Electrocatalysts

Abstract

Three 40 wt % Pt/C electrocatalysts prepared using two different approaches—the polyol process and electrochemical dispersion of platinum under pulse alternating current—and a commercial Pt/C catalyst (Johnson Matthey prod.) were examined via X-ray diffraction (XRD) and transmission electron microscopy (TEM). The stability characteristics of the Pt/C catalysts were studied via long-term cycling, revealing that, for all cycling modes, the best stability was achieved for the Pt/C catalyst with the largest platinum nanoparticle sizes, which was synthesized via electrochemical dispersion of platinum under pulse alternating current. Our results show that the mass and specific electrocatalytic activities of Pt/C catalysts toward ethanol electrooxidation are determined by the value of the electrochemically active Pt surface area in the catalysts.

Solution‐Processed Graphene Thin‐Film Enables Binder‐Free, Efficient Loading of Nanocatalysts for Electrochemical Water Splitting

“…[ 3 ] The state‐of‐the‐art water splitting cells use nanoparticles of platinum or other noble metals (e.g., ruthenium and iridium) coated onto porous carbon electrodes that conduct electricity and facilitate release of gas bubbles. [ 4 ] Although these systems demonstrated excellent catalytic performance with high electrolytic current density at an overpotential close to the thermodynamic equilibrium potential, high cost, and scarcity of the noble metals impeded their widespread use. [ 4b ] Alternatively, transition‐metal‐based nanocatalysts such as transition metal sulfides and oxides have been extensively investigated.…”

“…[ 4 ] Although these systems demonstrated excellent catalytic performance with high electrolytic current density at an overpotential close to the thermodynamic equilibrium potential, high cost, and scarcity of the noble metals impeded their widespread use. [ 4b ] Alternatively, transition‐metal‐based nanocatalysts such as transition metal sulfides and oxides have been extensively investigated. [ 5 ] For example, 2D molybdenum disulfide (MoS 2 ) nanosheets have shown promise as HER catalysts because of their rich active sites resulting from under‐coordinated Mo atoms at the edges.…”

“…Reducing the size of nanocatalysts is advantageous for enhancing the water splitting performance because the electrochemical reactions mostly occur at the surface of nanoparticles or edges of 2D nanosheets. [ 4b,6a,7 ] In most cases, active electrodes are created by drop casting solution containing the catalysts and polymeric binders onto porous carbon substrates. [ 8 ] One drawback of this strategy, however, is that uniform coating of nanocatalysts without aggregation is difficult especially at high mass loadings.…”

“…For example, noble metal nanoparticles or 2D nanosheets of transition metal disulfides and hydroxides could form on the porous conductive substrate and showed enhanced catalytic activity compared to binder‐processed nanocatalysts. [ 4b,7,11 ] However, applicability of this method for producing water‐splitting electrodes is limited because 1) sophisticated techniques such as chemical vapor deposition and high‐temperature reactions at controlled pressure are needed and 2) different synthesis schemes should be developed for different combinations of electrode and catalyst materials.…”

A Study on the Dynamic Forming Mechanism Development of the Negative Poisson’s Ratio Elastomer Molds—Plate to Plate (P2P) Forming Process

“…Aaron et al [ 6 ] developed a method to accurately culture cells with PDMS. Moreover, the micro/nano-structural substrates of different sizes and shapes [ 7 , 8 ] prepared by different processing methods (top-down, bottom-up) have high SERS enhancement factors and can be used for medical detection. At present, microstructural components, such as micro-nano gratings [ 9 , 10 , 11 , 12 , 13 , 14 ], polarizers, and lenses, can be completed by technologies such as nano-imprint, exposure, and development [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ].…”