The Co–Pi cocatalyst improves the PEC performance of a hematite film by accelerating the H2O oxidation kinetics and suppressing the charge recombinations.
Silicon
photovoltaic cells functionalized with water-splitting
electrocatalysts are promising
candidates for unassisted water splitting. In these devices, the total
surface of silicon solar cells is covered with electrocatalysts, causing
issues with (i) stabilizing silicon solar cells in water and (ii)
device efficiency due to parasitic optical absorption in electrocatalysts.
We describe and validate a water-splitting device concept using a
crystalline silicon solar cell where the front side is covered with
an insulating Si3N5 antireflection coating.
The Ag contacts, fired through the antireflection coating, are removed
and subsequently substituted with NiFe layered double hydroxide (LDH)
or Cu/NiFe-LDH electrocatalysts. In this device, only the site of
Ag contacts, nearly 2% of the total device area, is covered by the
electrocatalyst. We found that this small area of the catalyst does
not limit device performance and the addition of a Cu interlayer between
Si and NiFe-LDH improves device performance and stability. The unassisted
water-splitting efficiency of 11.31%, measured without separating
the evolved gases, is achieved using a device composed of three series-connected
silicon solar cells and an NiFe-LDH/Cu/Ni-foam counter electrode in
a highly alkaline electrolyte.
In this paper, a plasmonic refractive index sensor using a D-shaped optical fiber coated by tantalum has been proposed. The interaction between fiber fundamental mode and plasmonic mode which lead to the formation of resonance peaks depending on the analyte refractive index (RI) are investigated in detail. Using spectral sensitivity methods, the sensing performance of the proposed sensor for detecting analytes is numerically studied. The effect of various design parameters of proposed sensor are optimized numerically to achieve the maximum wavelength sensitivity. The proposed D-shaped optical fiber sensor has a RI detection range of 1.30 to 1.43 and exhibits a non-linear increasing spectral sensitivity from 1300 nm/RIU to 3900 nm/RIU. The proposed RI sensor is attractive for detecting different RI chemical and biochemical samples due to simple design, relatively large detection range, cost-effective, non-toxic nature and highly corrosion resistivity plasmonic material.
The water oxidation efficiency of hematite photoanodes is mainly limited by low visible light absorption and short hole diffusion length. Herein, we report on production of nanoporous columnar hematite films modified with Au nanoparticles (NPs) to overcome these drawbacks. The hematite films are prepared by electron beam evaporation. By optimization of deposition conditions including film thickness, annealing and performing the evaporation under oblique angle, an efficient photoelectrochemical (PEC) performance is achieved from the pristine hematite photoanode. Then, Au NPs are infiltrated into the hematite films by a spin coating process. The water oxidation of hematite films is further enhanced after Au modification. The most efficient electrode generates a photocurrent density of 2.7 mA cm−2 at 1.5 V (RHE), showing about two‐fold improvement relative to that of bare hematite. Optical and electrochemical analyses suggest that the improvement after Au modification can be attributed to plasmonic and facilitating surface charge transfer. The contributions of different plasmonic mechanisms to the photocurrent enhancement are qualitatively discussed based on optical characterization and electromagnetic simulations. Electrochemical impedance spectroscopy is carried out to confirm the improvement of surface charge transport by the Au NPs. Our findings show that Au modification is a favorable strategy to improve the PEC performance of hematite photoanodes prepared by PVD methods.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.