Segmentation and Re-encapsulation of Porous PtCu Nanoparticles by Generated Carbon Shell for Enhanced Ethylene Glycol Oxidation and Oxygen-Reduction Reaction

Carbon encapsulated nanoparticles: materials science and energy applications

The technological implementation of electrochemical energy conversion and storage necessitates the acquisition of high-performance electrocatalysts and electrodes. Carbon encapsulated nanoparticles have emerged as an exciting option owing to their unique advantages that strike a high-level activity-stability balance. Ever-growing attention to this unique type of material is partly attributed to the straightforward rationale of carbonizing ubiquitous organic species under energetic conditions. In addition, on-demand precursors pave the way for not only introducing dopants and surface functional groups into the carbon shell but also generating diverse metal-based nanoparticle cores. By controlling the synthetic parameters, both the carbon shell and the metallic core are facilely engineered in terms of structure, composition, and dimensions. Apart from multiple easy-to-understand superiorities, such as improved agglomeration, corrosion, oxidation, and pulverization resistance and charge conduction, afforded by the carbon encapsulation, potential core-shell synergistic interactions lead to the fine-tuning of the electronic structures of both components. These features collectively contribute to the emerging energy applications of these nanostructures as novel electrocatalysts and electrodes. Thus, a systematic and comprehensive review is urgently needed to summarize recent advancements and stimulate further efforts in this rapidly evolving research field.

Hollow cage-like PtCu nanozyme-regulated photo-activity of porous CdIn2S4/SnO2 heterojunctions for ultrasensitive PEC sensing of streptomycin

Streptomycin (STR) is extensively employed for preventive and curative purposes in animals, which is accumulated in human body through food chain and induces serious health problems. Herein, highly photoactive type II heterojunctions of porous CdIn₂S₄/SnO₂ microspheres were initially prepared, which can effectively inhibit the recombination of the charge-hole pairs. Besides, the peroxidase-mimicking catalytic property of the hollow PtCu nanocages (PtCu NCs) was carefully investigated by UV-vis spectroscopy, where catalytic oxidation of tetramethylbenzidine behaved as the benchmarked reaction. On such basis, a highly selective photoelectrochemical (PEC) aptasensor was established with the CdIn₂S₄/SnO₂ heterojunctions for bioanalysis of streptomycin, coupled by the PtCu NCs nanozyme-catalyzed biocatalytic precipitation to achieve signal magnification. Specifically, the home-made nanozyme was applied for catalytic oxidation of 3,3'-diaminobenzidine to generate insulating precipitate in aqueous H₂O₂ system and thereby block the light harvesting on the photoanode, showing steeply declined PEC responses. The as-built aptasensor showed a broad linear range of 0.01-200 nM with a low limit of detection of 7.50 pM (S/N = 3) for such analysis, combined by exploring its practical detection in milk samples. This work shows excellent nanozyme-catalyzed signal amplification for fabrication of ultrasensitive PEC biosensors towards other antibiotics detection.

Role of the Potential Range during Stress Testing of Platinum-Containing Electrocatalysts at Elevated Temperature

The durability of low temperature proton exchange membrane fuel cell (PEMFC) catalysts crucially affects their lifetime. The choice of carbon support is important in terms of increasing the stability of catalysts. In this research, Pt/C samples were obtained using the polyol synthesis method on two types of carbon supports: the standard support, Vulcan XC-72, and carbon support with a high degree of graphitization, ECS-002402. One method for assessing structural characteristics is through transmission electron microscopy (TEM), according to which materials G1 and G2 showed an average nanoparticle size of 3.7 and 4.2 nm, respectively. On all catalysts, the oxygen reduction reaction proceeded according to the four electron mechanism. Durability was assessed by changes in ESA and activity in the ORR after 1000 cycles, with changes in the upper potential values: 0.7; 1.0; 1.2; and 1.4 V. After accelerated stress testing, the G1 material showed the greatest residual activity at a potential of 1.4 V (165 A/g (Pt). Based on the results of comparing various ADT protocols, the optimal mode of 0.4 and 1.4 V was chosen, and should be used for further studies comparing the durability of Pt/C catalysts.

Platinum-Containing Nanoparticles on N-Doped Carbon Supports as an Advanced Electrocatalyst for the Oxygen Reduction Reaction

New highly active electrocatalysts were obtained by depositing bimetallic Pt-Cu nanoparticles on the surface of an N-doped carbon support. The structural–morphological characteristics and electrochemical behavior of the catalysts were studied. Using current stress testing protocols, their resistance to degradation was assessed in comparison with that of a commercial Pt/C material. A combined approach to catalyst synthesis that consists in alloying platinum with copper and doping the support makes it possible to obtain catalysts with a uniform distribution of bimetallic nanoparticles on the carbon surface. The obtained catalysts exhibit high activity and durability.

Emerging carbon shell-encapsulated metal nanocatalysts for fuel cells and water electrolysis

The development of low-cost, high-efficiency electrocatalysts is of primary importance for hydrogen energy technology. Noble metal-based catalysts have been extensively studied for decades; however, activity and durability issues still remain a challenge. In recent years, carbon shell-encapsulated metal (M@C) catalysts have drawn great attention as novel materials for water electrolysis and fuel cell applications. These electrochemical reactions are governed mainly by interfacial charge transfer between the core metal and the outer carbon shell, which alters the electronic structure of the catalyst surface. Furthermore, the rationally designed and fine-tuned carbon shell plays a very interesting role as a protective layer or molecular sieve layer to improve the performance and durability of energy conversion systems. Herein, we review recent advances in the use of M@C type nanocatalysts for extensive applications in fuel cells and water electrolysis with a focus on the structural design and electronic structure modulation of carbon shell-encapsulated metal/alloys. Finally, we highlight the current challenges and future perspectives of these catalytic materials and related technologies in this field.

Highly Active Hollow RhCu Nanoboxes toward Ethylene Glycol Electrooxidation

The efficient electrocatalysts toward the ethylene glycol oxidation reaction (EGOR) are highly desirable for direct ethylene glycol fuel cells because of the sluggish kinetics of anodic EGOR. Herein, porous RhCu nanoboxes are successfully prepared through facile galvanic replacement reaction and succedent sodium borohydride reduction strategy. Benefiting from hierarchical pore structure, RhCu nanoboxes display excellent electrocatalytic performance toward the EGOR in alkaline medium with a mass activity of 775.1 A g_Rh ^-1 , which is 2.8 times as large as that of commercial Rh nanocrystals. Moreover, the long-term stability of RhCu nanoboxes is better than that of commercial Rh nanocrystals. Furthermore, the theoretical calculations demonstrate that RhCu nanoboxes possess lower adsorption energy of CO and lower reaction barrier (0.27 eV) for the CO_ads oxidation with aid of the adsorbed OH_ads species, resulting in the outstanding electrocatalytic performance toward the EGOR. This work provides a meaningful reference for developing highly effective electrocatalysts toward the EGOR.