@article {1087, title = {Highly efficient and durable III{\textendash}V semiconductor-catalyst photocathodes via a transparent protection layer}, journal = {Sustainable Energy Fuels}, volume = {4}, year = {2020}, pages = {1437-1442}, abstract = {

Durable performance and high efficiency in solar-driven water splitting are great challenges not yet co-achieved in photoelectrochemical (PEC) cells. Although photovoltaic cells made from III{\textendash}V semiconductors can achieve high optical{\textendash}electrical conversion efficiency, their functional integration with electrocatalysts and operational lifetime remain great challenges. Herein, an ultra-thin TiN layer was used as a diffusion barrier on a buried junction n+p-GaInP2 photocathode, to enable elevated temperatures for subsequent catalyst growth of Ni5P4 as nano-islands without damaging the GaInP2 junction. The resulting PEC half-cell showed negligible absorption loss, with saturated photocurrent density and H2 evolution equivalent to the benchmark photocathode decorated with PtRu catalysts. High corrosion-resistant Ni5P4/TiN layers showed undiminished photocathode operation over 120 h, exceeding previous benchmarks. Etching to remove electrodeposited copper, an introduced contaminant, restored full performance, demonstrating operational ruggedness. The TiN layer expands the synthesis conditions and protects against corrosion for stable operation of III{\textendash}V PEC devices, while the Ni5P4 catalyst replaces costly and scarce noble metal catalysts.

}, doi = {10.1039/C9SE01264H}, url = {http://dx.doi.org/10.1039/C9SE01264H}, author = {Shinjae Hwang and James L. Young and Rachel Mow and Anders B. Laursen and Mengjun Li and Hongbin Yang and Philip E. Batson and Martha Greenblatt and Myles A. Steiner and Daniel Friedman and Todd G. Deutsch and Eric Garfunkel and G. Charles Dismukes} } @article {1083, title = {Creating stable interfaces between reactive materials: titanium nitride protects photoabsorber{\textendash}catalyst interface in water-splitting photocathodes}, journal = {Journal of Materials Chemistry A}, volume = {7}, year = {2019}, pages = {2400-2411}, abstract = {

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 ({\textpm}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.

}, issn = {2050-7496}, doi = {10.1039/C8TA12186A}, url = {https://pubs.rsc.org/en/content/articlelanding/2019/ta/c8ta12186a}, author = {Shinjae Hwang and Spencer H. Porter and Anders B. Laursen and Hongbin Yang and Mengjun Li and Viacheslav Manichev and Karin U. D. Calvinho and Voshadhi Amarasinghe and Martha Greenblatt and Eric Garfunkel and G. Charles Dismukes} }