Enhanced H2O2 production via photocatalytic O2 reduction over structurally-modified poly(heptazine imide)

Sharma, Pankaj ORCID: https://orcid.org/0000-0003-2319-260X, Slater, Thomas J. A. ORCID: https://orcid.org/0000-0003-0372-1551, Sharma, Monika, Bowker, Michael ORCID: https://orcid.org/0000-0001-5075-1089 and Catlow, C. Richard A. ORCID: https://orcid.org/0000-0002-1341-1541 2022. Enhanced H2O2 production via photocatalytic O2 reduction over structurally-modified poly(heptazine imide). Chemistry of Materials 34 (12) , pp. 5511-5521. 10.1021/acs.chemmater.2c00528

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Abstract

Solar H2O2 produced by O2 reduction provides a green, efficient, and ecological alternative to the industrial anthraquinone process and H2/O2 direct-synthesis. We report efficient photocatalytic H2O2 production at a rate of 73.4 mM h–1 in the presence of a sacrificial donor on a structurally engineered catalyst, alkali metal-halide modulated poly(heptazine imide) (MX → PHI). The reported H2O2 production is nearly 150 and >4250 times higher than triazine structured pristine carbon nitride under UV–visible and visible light (≥400 nm) irradiation, respectively. Furthermore, the solar H2O2 production rate on MX → PHI is higher than most of the previously reported carbon nitride (triazine, tri-s-triazine), metal oxides, metal sulfides, and other metal–organic photocatalysts. A record high AQY of 96% at 365 nm and 21% at 450 nm was observed. We find that structural modulation by alkali metal-halides results in a highly photoactive MX → PHI catalyst which has a broader light absorption range, enhanced light absorption ability, tailored bandgap, and a tunable band edge position. Moreover, this material has a different polymeric structure, high O2 trapping ability, interlayer intercalation, as well as surface decoration of alkali metals. The specific C≡N groups and surface defects, generated by intercalated MX, were also considered as potential contributors to the separation of photoinduced electron–hole pairs, leading to enhanced photocatalytic activity. A synergy of all these factors contributes to a higher H2O2 production rate. Spectroscopic data help us to rationalize the exceptional photochemical performance and structural characteristics of MX → PHI.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Additional Information:	CC-BY
Publisher:	American Chemical Society
ISSN:	0897-4756
Funders:	European Union�s Horizon 2020 Research and Innovation Programme, EPSRC
Date of First Compliant Deposit:	15 June 2022
Date of Acceptance:	19 May 2022
Last Modified:	24 May 2023 18:48
URI:	https://orca.cardiff.ac.uk/id/eprint/150524

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