Title: Microwave-Assisted Synthesis of Cu@IrO₂ Core-Shell Nanowires for Low-Temperature Methane Conversion

Abstract

A facile microwave-assisted synthesis was developed for the tunable fabrication of a novel Cu@IrO₂ core@shell nanowire motif. Experimental parameters, such as (i) reaction time, (ii) the method of addition of the Ir precursor, (iii) capping agent, (iv) reducing agent, as well as (v) the capping agent-to-reducing agent ratio, were subsequently optimized. The viability of other methods based on previously reported literature, such as refluxing, stirring, and physical sonication, was studied and compared with our optimized microwave-assisted protocol in creating our as-prepared materials. It should be noted that the magnitude of the IrO₂ shell could be tailored based on varying the Cu: Ir ratio coupled with judicious variations in the amounts of capping agent and reducing agent. Structural characterization techniques, such as XRD, XPS, and HRTEM (including HRTEM-EDS), were used to analyze our Cu@IrO₂ motifs. Specifically, the shell could be reliably tailored from sizes of 10 nm, 8 nm, 6 nm, and 3.5 nm with corresponding Cu: Ir ratios of 10:1, 15:1, 20:1, and 25:1, respectively. Moreover, the structural integrity of the motifs was probed and found to have been maintained after not only heat treatment but also the post-methane conversion process, indicative of an intrinsically high stability. Both components withinmore » the CuO-IrO₂ interface were able to activate methane at temperatures between 400 to 500 K with a reduction of the associated metal cations (Cu²⁺ → Cu¹⁺; Ir⁴⁺ → Ir³⁺) and the deposition of CH_x fragments on the surface, as clearly observed in the ambient-pressure XPS results. Thus, on the basis of their stability and chemical activity, these core-shell materials could be very useful for the catalytic conversion of methane into 'higher value" chemicals.« less

Authors:

Salvatore, Kenna L. ^[1]; Deng, Kaixi ^[2]; McGuire, Scott C. ^[1]; Tan, Sha  ^[1];

• Search DOE PAGES for author "Tan, Sha"
• Search DOE PAGES for ORCID "0000-0001-8277-893X"

Rui, Ning  ^[3];

• Search DOE PAGES for author "Rui, Ning"
• Search DOE PAGES for ORCID "0000-0001-6234-7075"

Zhang, Lihua ^[4]; Rodriguez, José A.  ^[3];

• Search DOE PAGES for author "Rodriguez, José A."
• Search DOE PAGES for ORCID "0000-0002-5680-4214"

Wong, Stanislaus S.  ^[1]

• Search DOE PAGES for author "Wong, Stanislaus S."
• Search DOE PAGES for ORCID "0000-0001-7351-0739"

---

+ Show Author Affiliations

1. State Univ. of New York (SUNY), Stony Brook, NY (United States)
2. State Univ. of New York (SUNY), Stony Brook, NY (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
3. Brookhaven National Lab. (BNL), Upton, NY (United States)
4. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)

Publication Date:

Wed Oct 13 00:00:00 EDT 2021

Research Org.:

Brookhaven National Laboratory (BNL), Upton, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1825728

Report Number(s):

BNL-222233-2021-JAAM
Journal ID: ISSN 2574-0970

Grant/Contract Number:  

SC0012704; CHE-1807640

Resource Type:

Accepted Manuscript

Journal Name:

ACS Applied Nano Materials

Additional Journal Information:

Journal Volume: 4; Journal Issue: 10; Journal ID: ISSN 2574-0970

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Methane; Copper oxide; Iridium oxide; Hydrocarbons; Precursors; Nanoparticles; Catalysts; Transition metals