Confinement Effects in Individual Carbon Encapsulated Nonprecious Metal‐Based Electrocatalysts

Abstract

The evolution of cost-effective and reserve-rich nonprecious metals (NPMs) to replace precious metal electrocatalysts is of significant interest in modern electrocatalysis. The confinement effects in NPM-based nanoparticles encapsulated in carbon nanoshells have been considered as an emerging and efficient way to special types of electrocatalysts which facilitate electrocatalytic activity and stability, even under rigorous conditions. This review focuses on the unique individual carbon encapsulation for high-performance design of NPM-based electrocatalysts, outlining all confinement synthesis methods, mechanistic studies on confinement effects, and the emerging practical reactions. It begins first introducing the synthetic methods for NPM-based core@carbon shell electrocatalysts, and then follows clarification of the relationship between the fundamental confinement effects and the performance improvement of carbon shell encapsulating NPM-based electrocatalysts. Further and detailed discussions on the alloying effect, doping effect, and heterojunction effect of the NPM-based core to alter the electronic situation which affects the electrocatalytic performance are subsequently provided. Finally, the review provides a perspective on challenges and opportunities in future research with respect to both in-depth theoretical research and potential design concept of such NPM-based core@carbon shell electrocatalysts.

Following the Kinetics of Undercover Catalysis with APXPS and the Role of Hydrogen as an Intercalation Promoter

“…In particular, we expect pulsing experiments to provide a better understanding of the limitations in catalyst reactivity induced by mass transport limitations. Ultimately, we hope that pulsing experiments will become a compelling method for tracking the underlying reason for the increased undercover activity reported below several 2D materials. ,,,, …”

“…Ultimately, we hope that pulsing experiments will become a compelling method for tracking the underlying reason for the increased undercover activity reported below several 2D materials. 4,12,13,15,16 Finally, we wish to highlight that the present work uses very simple gas-composition pulses consisting of H 2 :O 2 , CO:O 2 , and combined H 2 :CO:O 2 mixtures. Future experiments may use more complex pulsing schemes such as gas-composition pulses offset in time or even gas pulses combined with temperature pulses as additional drivers for the intercalation and deintercalation of species or the ignition of undercover reactions.…”

“…The reactivity of the catalytic support can be enhanced due to the confinement of the adsorbates, which results in the modification of the relevant electronic states. This phenomenon has been studied for multiple reactions in a variety of systems ,,, such as graphene-covered nanoparticles, , covered polycrystalline surfaces, for solution-phase reactions, and under a variety of 2D materials other than graphene. − Moreover, with such novel model systems, one can obtain a fundamental atomic-scale understanding of confined chemistry, similar to the approach developed by Ertl for noncovered catalytic surfaces …”

Superior Electrocatalysis Delivered by a Directional Electron Transfer Cascade in Hierarchical CoNi/Ru@C

“…Confined nanostructures are perfect candidates for inducing such electron transfer cascades. [21][22][23][24][25][26][27] Consider, for example, an inorganic electron transfer chain where a CoNi alloy acts as the electron donor (with Co and Ni having electronegativities of 1.88 and 1.91, respectively), carbon as the electron acceptor (electronegativity = 2.50) and Ru (electronegativity = 2.20) in the middle. Herein, just such a CoNi/Ru@C spatial junction has been designed and synthesised.…”

A facile synthesis of hierarchically porous graphene for high-performance lithium storage

“…[4][5][6] Currently, HPG has been fabricated either from graphene oxide by self-assembly and 3D printing, or via chemical vapor deposition (CVD) and polymerization of nongaseous hydrocarbons. 7,8 In these 3D structures, macropores are formed between nanosheets via cross-linking gelation or a template drive, giving the graphene frameworks structural diversity and functional versatility. Moreover, nanopores can be formed on the surface of the graphene sheets in HPG frameworks by using H 2 O 2 , HCl or other etching agents to improve the ion transfer rate during the charge/discharge process.…”