Identification of Facet‐Governing Reactivity in Hematite for Oxygen Evolution. Issue 52 (2nd November 2018)

• Record Type: Journal Article
• Authors: Wu, Hao; Yang, Tong; Du, Yonghua; Shen, Lei; Ho, Ghim Wei
• Is Part Of: Advanced materials. Volume 30:Issue 52(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-11-02
• Subjects: descriptors -- facets -- hematite -- oxygen evolution reaction -- reactivity; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201804341
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Unveiling the impact of a single parameter on the catalytic descriptor is fundamental to guide rational design principles for high‐activity catalysts. Facets with distinct surface coordination that exhibit a central role in the kinetics modulation (reactivity) of surface electrochemistry, have remained elusive in oxygen evolution reactions (OERs). Here, the relationship between the predominant facets and catalytic reactivity is revealed, and it is recognized that facets decisively govern the oxygen evolution activity descriptor in hematite nanocrystals. Specifically, the hematite shows facet‐dependent activity that follows the computed binding energy of surface‐oxygenated intermediates. Moreover, a lower kinetics energy barrier is observed on a highly coordinated surface, both experimentally and computationally, in the light of molecular orbital principles. Consequently, a record‐low overpotential and Tafel slope in iron oxides toward OER are manifested, competing against the benchmark binary transition metal oxide electrocatalysts and expelling the stereotype of the passive oxygen evolution activity of iron oxides. Significantly, the identification of facet‐governing reactivity, construction of favorable facets, and strategic regulation of surface covalency enlighten design strategies for highly active catalysts. Abstract : Facet‐governing reactivity toward oxygen evolution is identified in hematites, where three facet‐enclosed nanocrystals show distinct activity that follows computed trends. The favorable high‐index (012) facet hematite nanocrystal exhibits high activity, expelling the stereotype passiveness of iron oxides toward oxygen evolution.