Stable solar water splitting with wettable organic-layer-protected silicon photocathodes

Abstract

Protective layers are essential for Si-based photocathodes to achieve long-term stability. The conventionally used inorganic protective layers, such as TiO2, need to be free of pinholes to isolate Si from corrosive solution, which demands extremely high-quality deposition techniques. On the other hand, organic hydrophobic protective layers suffer from the trade-off between current density and stability. This paper describes the design and fabrication of a discontinuous hybrid organic protective layer with controllable surface wettability. The underlying hydrophobic layer induces the formation of thin gas layers at the discontinuous pores to isolate the electrolyte from Si substrate, while allowing Pt co-catalyst to contact the electrolyte for water splitting. Meanwhile, the surface of this organic layer is modified with hydrophilic hydroxyl groups to facilitate bubble detachment. The optimized photocathode achieves a stable photocurrent of 35 mA/cm2 for over 110 h with no trend of decay.

Aqueous Photoelectrochemical CO2Reduction to CO and Methanol over a Silicon Photocathode Functionalized with a Cobalt Phthalocyanine Molecular Catalyst

“…When the illumination power was increased, the QE was observed to drop rapidly. This may indicate that charge separation of p‐Si or the catalyst turnover rate may be limiting the QE under high‐power illumination, limitations that could be overcome by constructing p‐n junction photocathodes or by developing more active catalyst materials [6, 17, 31] …”

Aqueous Photoelectrochemical CO2Reduction to CO and Methanol over a Silicon Photocathode Functionalized with a Cobalt Phthalocyanine Molecular Catalyst

“…This may indicate that charge separation of p-Si or the catalyst turnover rate may be limiting the QE under high-power illumination, limitations that could be overcome by constructing p-n junction photocathodes or by developing more active catalyst materials. [6,17,31] In summary, for the first time, we demonstrate aqueous PEC CO 2 reduction to MeOH at a molecular catalystmodified Si photocathode. Additionally, the as-constructed STA-GO/CoPc photoelectrodes produce CO with high selectivity at ultralow overpotential owing to a photovoltage estimated to be greater than 0.5 V. The onset potential of CO generation is 0 V and an optimal FE CO of 86 % is achieved.…”

Boosting Oxygen Reduction through Microenvironment Modulation to Enhance Mass Transportation

“…Specifically, a contact angle of 140°w as employed for CNT-NH 2 /PTFE, while a contact angle of 85°was used for pure CNT-NH 2 . The momentum equations governing the entirety of the flow field are expressed as follows [51] ρ…”

“…Specifically, a contact angle of 140° was employed for CNT‐NH 2 /PTFE, while a contact angle of 85° was used for pure CNT‐NH 2 . The momentum equations governing the entirety of the flow field are expressed as follows [ 51 ] …”