Decentralized on-site production of hydrogen peroxide (H2O2) relies on efficient, robust, and inexpensive electrocatalysts for the selective two-electron (2e-) oxygen reduction reaction (ORR). Here, we combine computations and experiments to demonstrate that cobalt pyrite (CoS2), an earth-abundant transition-metal compound, is both active and selective toward 2e- ORR in the acidic solution. CoS2 nanomaterials drop-casted on the rotating ring-disk electrode (RRDE) showed selective and efficient H2O2 formation in 0.05 M H2SO4 at high catalyst loadings, with their operational stability evaluated by structural and surface analyses. CoS2 nanowires directly grown on the high-surface-area carbon fiber paper electrode boosted the overall performance of bulk ORR electrolysis and the H2O2 product was chemically quantified to yield a â¼70% H2O2 selectivity at 0.5 V vs reversible hydrogen electrode (RHE), in good agreement with the RRDE results. Computations suggested the modest binding of OOH∗ adsorbate on the single Co site of CoS2 and the kinetically disfavored O-O bond scission due to the lack of active site ensembles in the crystal structure, consistent with the experimentally observed activity and selectivity. CoS2 also catalyzes 2e- ORR with less activity and selectivity in the noncorrosive neutral solution. This work opens up the exploration of diverse earth-abundant transition-metal compounds in search of highly active and selective electrocatalysts for efficient H2O2 production.
|Original language||English (US)|
|Number of pages||10|
|State||Published - Aug 2019|
Bibliographical noteKAUST Repository Item: Exported on 2021-03-12
Acknowledged KAUST grant number(s): OSR-2017-CRG6-3453.02
Acknowledgements: This research was partially supported by the National Science Foundation (NSF) Grant DMR-1508558 (H.S., W.L., and S.J.) for the material synthesis, by University of Wisconsin-Madison and King Abdullah University of Science and Technology (KAUST) OSR-2017-CRG6-3453.02 (H.S., W.L., and S.J.) for the electrochemical characterization, and CHE-1362136 (E.D.H, A.N.J., and J.R.S.) for the theoretical calculation.
X.Y. and D.Y. thank the China Scholarship Council (CSC) and the National Natural Science Foundation of China (NSFC) Grant 51608319 for support. The authors gratefully acknowledge use of facilities and instrumentation supported by NSF through the University of Wisconsin Materials Research Science and Engineering Center (DMR-1720415).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
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