Carbon-supported ultrafine Pt nanoparticles modified with trace amounts of cobalt as enhanced oxygen reduction reaction catalysts for proton exchange membrane fuel cells

Pt3(CoNi) Ternary Intermetallic Nanoparticles Immobilized on N-Doped Carbon Derived from Zeolitic Imidazolate Frameworks for Oxygen Reduction

Pt-based intermetallic compound (IMC) nanoparticles have been considered the most promising catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). Herein, we propose a strategy for producing ordered Pt3(CoNi) ternary IMC nanoparticles supported on N-doped carbon materials. Particularly, the Co and Ni are originally embedded into ZIF-derived carbon, which diffuse into Pt nanocrystals to form Pt3(CoNi) nanoparticles. Moreover, a thin layer of carbon develops outside of Pt3(CoNi) nanoparticles during the cooling process, which contributes to stabilizing the Pt3(CoNi) on carbon supports. The optimal Pt3(CoNi) nanoparticle catalyst has achieved significantly enhanced activity and stability, exhibiting a half-wave potential of 0.885 V vs reversible hydrogen electrode (RHE) and losing only 16 mV after 10,000 potential cycles between 0.6 and 1.0 V. Unlike the direct-use commercial carbon (VXC-72) for depositing Pt, we utilized ZIF-derived carbon containing dispersed Co and Ni nanocluster or nanoparticles to prepare ordered Pt3(CoNi) intermetallic catalysts.

Atomic Ru-Pt dual sites boost the mass activity and cycle life of alkaline hydrogen evolution

The development of highly efficient and ultrastable electrocatalysts for hydrogen generation from water/real seawater faces huge challenges. Herein, porous carbon-supported amorphous RuPt nanoclusters (Ru5.67Pt/PC) achieve mass activities of 42.28/10.93 A mgPt-1 and ultralong cycling stability in alkaline water/seawater because of the unique cluster structure and atomic Ru-Pt dual sites.

A facile strategy to prepare FeNx decorated PtFe intermetallic with excellent acidic oxygen reduction reaction activity and stability

The construction of low-Pt-content intermetallic on carbon supports has been verified as a promising method to promote the activity of the oxygen reduction reaction (ORR). In this study, we have developed a simple and effective strategy to obtain a well-designed CNT-PtFe-PPy precursor. This precursor contains modulated Pt- and Fe-based content dispersed in polypyrrole (PPy) chain segments, which are in-situ generated on the templates of carbon nanotubes (CNTs). Subsequent pyrolysis of the CNT-PtFe-PPy precursor produces a CNT-PtFe@FeNC catalyst, which contains both Fe-N_x and PtFe intermetallic active sites. Due to the highly efficient dispersion of active species, the CNT-PtFe@FeNC electrocatalyst displays a 9.5 times higher specific activity (SA) and 8.5 times higher mass activity (MA) than those of a commercial Pt/C catalyst in a 0.1 M HClO₄ solution. Additionally, these results, combined with excellent durability (the SA and MA maintained 94 % and 91 % of initial activity after a 10-k cycle accelerated durability test), represent among the best performance achieved so far for Pt-based ORR electrocatalysts. Furthermore, density functional theory (DFT) calculations revealed that the presence of Fe-N₄ species reduces the adsorption energy between the PtFe intermetallic compound and OH*, accelerating the ORR process.

Electrochemical/visual microfluidic detection with a covalent organic framework supported platinum nanozyme-based device for early diagnosis of pheochromocytoma

The development of smart, portable, and sensitive devices for the monitoring of circulating tumor cells (CTCs) is essential to diagnose several diseases, including pheochromocytoma (PCC). Therefore, in this study, a dual-mode (electrochemical/visual) microfluidic device was designed for the rapid and sensitive detection of PCC-CTCs using a microfluidic chip for automatic cell sampling and detection and a smartphone-based three-dimensional-printed accessory for signal output analysis. The device was employed to capture and identify PCC-CTCs via specific immunogenic binding to the norepinephrine transporter and somatostatin receptor, which are overexpressed on the surface of PCC cells. Specifically, targeted-modified magnetic particles were used to capture and separate PCC-CTCs from peripheral blood; then, similarly modified covalent organic framework based nanozymes (COF@Pt) were used as peroxidase mimics to amplify the electrochemical response from H₂O₂ reduction and catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine by hydroxyl radicals in the presence of the PCC cells to enable visual quantification. Using the prepared microfluidic device, a low detection limit of 1 cell mL^-1 at a signal-to-noise ratio of 3 and a wide linear range of 2 to 10⁵ cells mL^-1 were achieved. Overall, this work demonstrates a portable, sensitive, and visual platform for PCC diagnostics that meets the requirement for quick and precise point-of-care diagnostics.

Investigation of multiple commercial electrocatalysts and electrocatalyst degradation for fuel cells in real vehicles

The coalescence of Pt nanoparticles during operation in a real vehicle is considered to be the main reason to weaken the ORR. The trajectories of oriented attachment were disclosed by observing the coalescence events of Pt NPs using in situ TEM.

Platinum-Decorated Ceria Enhances CO2 Electroreduction in Solid Oxide Electrolysis Cells

CO₂ electroreduction by solid oxide electrolysis cells (SOECs) can not only attenuate the greenhouse effect, but also convert surplus electrical energy into chemical energy. The adsorption and activation of CO₂ on the cathode play an important role in the SOEC performance. La_0.6 Sr_0.4 Co_0.2 Fe_0.8 O_3-δ -Ce_0.8 Sm_0.2 O_2-δ (LSCF-SDC; SDC=samarium-doped ceria) is a promising SOEC cathode. However, its electrocatalytic activity still needs to be improved. In this study, Pt/SDC interfaces are constructed by decorating Pt nanoparticles onto the SDC surface. Electrochemical measurements indicate that the polarization resistance of the SOEC is decreased from 0.308 to 0.120 Ω cm² , and the current density is improved from 0.913 to 1.420 A cm^-2 at 1.6 V and 800 °C. Physicochemical characterizations suggest that construction of the Pt/SDC interfaces increases the oxygen vacancy concentration on the cathode and boosts CO₂ adsorption and dissociation, which leads to enhanced CO₂ electroreduction performance in SOECs.

High-Loading Pt-Co/C Catalyst with Enhanced Durability toward the Oxygen Reduction Reaction through Surface Au Modification

Carbon-supported Pt-Co (Pt-Co/C) nanoparticles with a high Pt loading are regarded as promising cathode catalysts for practical applications of proton exchange membrane fuel cells (PEMFCs). Unfortunately, with high loading, it is difficult to improve the catalytic durability while maintaining the particle size between 2 and 5 nm to ensure the initial catalytic activity. Thus, it is of great significance to prepare high-loading Pt-Co/C catalysts with enhanced activity and durability. Herein, we proposed an efficient way to prepare high-Pt-loading (>50 wt %) Pt-Co/C catalysts without using any further surfactants. Furthermore, due to the one-step selective acid etching and surface Au modification, the as-prepared catalysts only need to undergo thermal treatment at as low as 150 °C to achieve a surface structure rich of Pt and Au. The average particle size of the as-prepared Au-Pt-Co/C-0.015 is 3.42 nm, and the Pt loading of it is up to 50.2 wt %. The atomic ratio of Pt, Co, and Au is 94:5:1. The mass activity (MA) is nearly 1.9 times that of Pt/C (60 wt %, JM) and the specific activity is also improved. The MA loss after the 30,000-cycle accelerated degradation test (ADT) is only 9.4%. The remarkable durability is mainly due to the surface Au modification, which can restrict the dissolution of Pt and Co. This research provides an effective synthesis strategy to prepare high-loading carbon-supported Pt-based catalysts beneficial to practical PEMFC applications.

Concave PtCo nanooctahedra with high-energy {110} facets for the oxygen reduction reaction

For the first time, iminodiacetic acid serves as a morphology control agent for the synthesis of concave PtCo nanooctahedra.