Creating stable interfaces between reactive materials: titanium nitride protects photoabsorber-catalyst interface in water-splitting photocathodes

Shinjae Hwang, Spencer H. Porter, Anders B. Laursen, Hongbin Yang, Mengjun Li, Viacheslav Manichev, Karin U.D. Calvinho, Voshadhi Amarasinghe, Martha Greenblatt, Eric Garfunkel, G Charles Dismukes

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The development of a solar-driven water splitting device that replaces costly precious metals, while achieving stable high performance, is a major challenge. Transition metal phosphides are active and low-cost catalysts for the hydrogen evolution reaction (HER), although, none thus far have exhibited stable performance when interfaced with semiconductors. Here, we report on a monolithic junction consisting of cubic-NiP2:TiN:Si, fabricated using both commercial and custom Si photovoltaics. Stable performance is achieved using an ultrathin film of crystalline TiN that effectively hinders atomic diffusion between interfaces during fabrication. Crystalline cubic-NiP2 deposited on TiN/n+p-Si retains 97% of the bare Si photovoltage, comparable saturation current density to bare Si, and has a turnover frequency of 1.04 H2 per site per s at -100 mV applied potential. In acid, it requires only -150 mV additional overpotential compared to the benchmark, Pt/TiN/n+p-Si, to reach a HER photocurrent density of -10 mA cm-2. This photocathode maintains a stable H2 photocurrent (±10%) for at least 125 hours, the duration of testing. When the same layers are fabricated on a commercial Si solar cell, this photocathode produced double the photocurrent density (36.3 mA cm-2, under simulated 1.5 AM G illumination). Physical characterization gives detailed information on the properties responsible for the observed activity and durability of these interfaces. In general, the thin-film methodology presented here is widely applicable, demonstrates superior activity, and achieves long-term stability.

Original languageEnglish
Pages (from-to)2400-2411
Number of pages12
JournalJournal of Materials Chemistry A
Volume7
Issue number5
DOIs
Publication statusPublished - Jan 1 2019

ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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