A three-dimensional ordered honeycomb nanostructure anchored with Pt–N active sites via self-assembly of a block copolymer: an efficient electrocatalyst towards the oxygen reduction reaction in fuel cells. Issue 22 (23rd May 2022)

• Record Type: Journal Article
• Authors: Wang, Zhida; Yang, Yi; Wang, Xiaoman; Lu, Zhuoxin; Guo, Changqing; Shi, Yan; Tan, Hongyi; Shen, Lisha; Cao, Shuo; Yan, Changfeng
• Is Part Of: Journal of materials chemistry. Volume 10:Issue 22(2022)
• Page Start: 12141
• Page End: 12149
• Publication Date: 2022-05-23
• Subjects: Materials -- Research -- Periodicals; Chemistry, Analytic -- Periodicals; Environmental sciences -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d2ta00752e
• Languages: English
• ISSNs: 2050-7488

Abstract

Abstract : A 3D N-doped ordered honeycomb nanostructure with Pt active sites (Pt/N-OHC), precisely controlled by the self-assembly of a block copolymer, provides a four-electron (4-e) transfer pathway and improved activity for the oxygen reduction reaction (ORR). Abstract : Mesoporous Pt-containing nanocomposites with well-organized pores are desirable for fuel cells as well as sensors, electronics, and various chemical reactions. However, it remains challenging to construct three-dimensional (3D) ordered honeycomb-like (OHC) nanostructures with Pt species anchored in the mesopores. Herein, we show for the first time an in situ strategy of developing an N-doped ordered honeycomb (N-OHC) nanopattern with well-dispersed Pt–N2 moieties by using the self-assembly of a block copolymer (BCP). The as-mentioned Pt including Pt single atoms (SAs) and Pt ∼2.5 nm ultrafine nanoparticles (NPs) was hierarchically located on the inner walls and the outer surfaces of the N-OHC mesopores (Pt/N-OHC), forming well-dispersed Pt–N active sites and showing efficient catalytic activity towards the oxygen reduction reaction (ORR). By changing the film thickness of the pristine Pt/BCP template, double-layered Pt/N-OHC could be designed and the ORR activity could be correspondingly improved, for which a current density of 1.60 A cm −2 @0.6 V and a peak power density of 1.07 W cm −2 were observed at a very low Pt-loading of 0.04 mg cm −2, better than 1.21 A cm −2 @0.6 V and 0.79 W cm −2 of the commercial Pt/C catalyst at a Pt-loading of 0.15 mg cm −2 . The electron donating behavior of Pt–N2 and the pathway for O2 reduction were investigated via the density functional theory (DFT) computation. The electron transfer from Pt to N gave rise to the formation of Pt–N covalent bonds, which resulted in a lower d band center and a weaker O adsorption energy and endowed the Pt/N-OHCs with enhanced ORR activity.