Optically and Electrocatalytically Decoupled Si Photocathodes with a Porous Carbon Nitride Catalyst for Nitrogen Reduction with Over 61.8% Faradaic Efficiency

Karthik Peramaiah, Vinoth Ramalingam, Hui-Chun Fu, Merfat Alsabban, Rafia Ahmad, Luigi Cavallo, Vincent Tung, Kuo-Wei Huang, Jr-Hau He

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

The photoelectrochemical (PEC) approach is attractive as a promising route for the nitrogen reduction reaction (NRR) toward ammonia (NH3 ) synthesis. However, the challenges in synergistic management of optical, electrical, and catalytic properties have limited the efficiency of PEC NRR devices. Herein, to enhance light-harvesting, carrier separation/transport, and the catalytic reactions, a concept of decoupling light-harvesting and electrocatalysis by employing a cascade n+ np+ -Si photocathode is implemented. Such a decoupling design not only abolishes the parasitic light blocking but also concurrently improves the optical and electrical properties of the n+ np+ -Si photocathode without compromising the efficiency. Experimental and density functional theory studies reveal that the porous architecture and N-vacancies promote N2 adsorption of the Au/porous carbon nitride (PCN) catalyst. Impressively, an n+ np+ -Si photocathode integrating the Au/PCN catalyst exhibits an outstanding PEC NRR performance with maximum Faradaic efficiency (FE) of 61.8% and NH3 production yield of 13.8 µg h-1 cm-2 at -0.10 V versus reversible hydrogen electrode (RHE), which is the highest FE at low applied potential ever reported for the PEC NRR.
Original languageEnglish (US)
Pages (from-to)2100812
JournalAdvanced Materials
DOIs
StatePublished - Mar 31 2021

Bibliographical note

KAUST Repository Item: Exported on 2021-04-05
Acknowledged KAUST grant number(s): OSR-2018-CARF/CCF-3079
Acknowledgements: K.P. and V.R. contributed equally to this work. This work was supported by the King Abdullah University of Science and Technology (KAUST) and City University of Hong Kong. V.T. is indebted to the support from the KAUST Office of Sponsored Research (OSR) under award no. OSR-2018-CARF/CCF-3079. R.A. and L.C. acknowledge the Supercomputing Laboratory at KAUST for computational resources (Cray XC40, ShaheenII).

ASJC Scopus subject areas

  • Mechanics of Materials
  • General Materials Science
  • Mechanical Engineering

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