• PDF / 1,120,225 Bytes
• 7 Pages / 595.28 x 785.2 pts Page_size
• 31 Downloads / 205 Views

DOWNLOAD

REPORT

---

Front. Phys. 16(1), 13503 (2021)

Research article Theoretical investigation of CoTa2 O6 /graphene heterojunctions for oxygen evolution reaction Qinye Li1,2 , Siyao Qiu3,† , Baohua Jia1,2,‡ 1

Centre for Translational Atomaterials, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia 2 The Australian Research Council (ARC) Industrial Transformation Training Centre in Surface Engineering for Advanced Materials (SEAM), Swinburne University of Technology, Hawthorn, Victoria 3122, Australia 3 College of Chemical Engineering and Energy Technology, Dongguan University of Technology, Dongguan 523808, China Corresponding authors. E-mail: † [email protected], ‡ [email protected] Received August 22, 2020; accepted September 8, 2020

Water electrolysis is to split water into hydrogen and oxygen using electricity as the driving force. To obtain low-cost hydrogen in a large scale, it is critical to develop electrocatalysts based on earth abundant elements with a high efficiency. This computational work started with Cobalt on CoTa2 O6 surface as the active site, CoTa2 O6 /Graphene heterojunctions have been explored as potential oxygen evolution reaction (OER) catalysts through density functional theory (DFT). We demonstrated that the electron transfer (δ) from CoTa2 O6 to graphene substrate can be utilized to boost the reactivity of Co-site, leading to an OER overpotential as low as 0.30 V when N-doped graphene is employed. Our findings offer novel design of heterojunctions as high performance OER catalysts. Keywords CoTa2 O6 , OER, charge transfer, DFT, heterojunctions

1 Introduction Water electrolysis has been identified as a promising approach to produce hydrogen from water [1–3]. However, the multistep oxygen evolution reaction (OER: 4OH− → 2H2 O + 4e− + O2 , E = 1.23 V versus Reversible Hydrogen Electrode, RHE) results in sluggish kinetics, which significantly limits its commercialization [2]. Currently, IrO2 and RuO2 have been widely recognized as the benchmark catalysts for OER. But their high costs restrict the industry large-scale applications [4–6]. Therefore, extensive efforts have been made to develop non-noble metalbased catalysts [7–12]. To develop low-cost alternative to IrO2 and RuO2 , a typical approach is to design OER catalysts with the use of earth abundant elements. Among various candidates, Cobalt (Co) has been widely identified as a promising element and widely explored, such as CoOOH-pristine [14], Ag@Co(OH)2 [15], Co3 O4 [16, 17], and highly dispersed Co embedded metal-organic-framework [18] and layered double hydroxides (LDH) [19]. These successes vividly demonstrated that Co–O bonding network offers high per∗ Special

Topic: Heterojunction and Its Applications (Ed. Chenghua Sun). This article can also be found at http:// journal.hep.com.cn/fop/EN/10.1007/s11467-020-0999-8.

formance for OER, but the catalysis performance is sensitive to the local bonding environment. A typical example is that the performances of Co3 O4 facets, due to coo