Title: Ultrathin alumina passivation for improved photoelectrochemical water oxidation catalysis of tin oxide sensitized by a phosphonate-functionalized perylene diimide first without, and then with, CoOy

Abstract

Previously, a photoanode composed of nanostructured SnO₂ coated with the perylene diimide dye N,N'-bis(phosphonomethyl)-3,4,9,10-perylenediimide (PMPDI) plus photoelectrochemically deposited cobalt oxide (CoO_y) was shown to photoelectrochemically oxidize water at 31 ± 7% faradaic efficiency. A non-ideal part of that prior system is that the addition of the known CoO_y water oxidation catalyst (WOC) resulted in a reduction of the total photocurrent rather than the anticipated increase, due to an increase in charge-carrier recombination. Herein, we show deposition of an ultrathin alumina overlayer applied by atomic layer deposition (ALD) on the SnO₂/PMPDI photoanode can improve the photoactivity and catalytic activity of the system; the addition a ca. 1 nm-thick AlO_x layer deposited on a 4000 nm (i.e., 4 micron) thick mesoporous anode system can and does have a positive, 2.5-fold improvement in the steady-state photocurrent with 29 ± 9% faradaic efficiency vs. the control anode without alumina passivation by reducing charge-carrier recombination. Moreover, ALD-deposited AlO_x layer does help support the understanding of the “anti-catalysis” of co-depositing a CoO_y WOC on the SnO₂/PMPDI DS-PECs—specifically the picture of direct CoO_y–SnO₂ contact-mediated recombination—but that AlO_x layer was unable to improve the photocurrent in a net SnO₂/PMPDI/AlO_x(/CoO_y) system. We attribute the lack of a performance enhancementmore » by CoOy WOC to incomplete coverage of each SnO₂ nanoparticle by the AlO_x. Overall, we find the addition of an optimized ultrathin AlOx layer (0.6 nm thick; deposited at 85 °C) improves the SnO₂/PMPDI/AlO_x system's photoactivity by a factor of up to ca. 3-fold with reduced recombination. These results document that metal-oxide passivation by low-temperature ALD can be an effective strategy for improving the water oxidation performance of even nanostructured dye sensitized-photoelectrochemical cell.« less

Authors:

Jewell, Carly F.  ^[1];

• Search DOE PAGES for author "Jewell, Carly F."
• Search DOE PAGES for ORCID "0000-0003-3177-3690"

Subramanian, Ashwanth  ^[2];

• Search DOE PAGES for author "Subramanian, Ashwanth"
• Search DOE PAGES for ORCID "0000-0003-1400-1533"

Nam, Chang-Yong  ^[3];

• Search DOE PAGES for author "Nam, Chang-Yong"
• Search DOE PAGES for ORCID "0000-0002-9093-4063"

Finke, Richard G.  ^[1]

• Search DOE PAGES for author "Finke, Richard G."
• Search DOE PAGES for ORCID "0000-0002-3668-7903"

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+ Show Author Affiliations

1. Colorado State Univ., Fort Collins, CO (United States)
2. Stony Brook Univ., NY (United States)
3. Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States)

Publication Date:

Wed Sep 22 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)

OSTI Identifier:

1830200

Report Number(s):

BNL-222376-2021-JAAM
Journal ID: ISSN 2398-4902

Grant/Contract Number:  

SC0012704

Resource Type:

Accepted Manuscript

Journal Name:

Sustainable Energy & Fuels

Additional Journal Information:

Journal Volume: 5; Journal Issue: 20; Journal ID: ISSN 2398-4902

Publisher:

Royal Society of Chemistry

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE