|Title||Creating stable interfaces between reactive materials: titanium nitride protects photoabsorber–catalyst interface in water-splitting photocathodes|
|Publication Type||Journal Article|
|Year of Publication||2019|
|Authors||Hwang S, Porter SH, Laursen AB, Yang H, Li M, Manichev V, Calvinho KUD, Amarasinghe V, Greenblatt M, Garfunkel E, G. Dismukes C|
|Journal||Journal of Materials Chemistry A|
Published on January 29th, 2019. 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.
Creating stable interfaces between reactive materials: titanium nitride protects photoabsorber–catalyst interface in water-splitting photocathodes
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