| Work Detail |
Korean scientists have built a prototype green hydrogen system that incorporates a photovoltaic generation unit based on perosvksite solar cell photoanodes. The device reportedly achieved a solar energy-to-hydrogen conversion efficiency of 9.8% for a device measuring 0.25 cm2, and 8.5% for a system measuring 123.2 cm2.
A group of researchers from South Koreas Ulsan National Institute of Science and Technology (UNIST) has designed a scalable photovoltaic-powered photoelectrochemical (PEC) system to produce green hydrogen that reportedly reaches a solar energy to hydrogen (STH) conversion efficiency of 9.8%.
“Our system is a first short-term demonstration attempt; We plan to modify the designs based on our upcoming research,” the lead author of the research, Dharmesh Hansora, told pv magazine . “The unique advantage of our system is the integration of multiple components into a single PEC device to avoid the additional use of photovoltaic components, which minimizes system complexity and reduces its cost.”
The system uses a photoanode made up of two photovoltaic cells made of a perovskite material known as formamidinium lead triiodide (FAPbI3). The photoanode is encapsulated in a nickel (Ni) foil and an electrocatalyst based on Ni, iron (Fe) and hydroperoxide (OOH).
The solar cells used for the photoanode have a pin structure and are based on a glass and fluorine-doped tin oxide (FTO) substrate. They are also based on a titanium dioxide (TiO2) electron transport layer (ETL), the perovskite absorber, a spiro-OMeTAD hole blocking layer and a gold (Au) metal contact.
The team also applied silver (Ag) paste as an ohmic bonding metal between the FAPbI3 layer and a passivation layer formed by a 25 µm thick Ni metal foil. The foil was used to completely block electrolyte permeation.
Next, the researchers deposited nickel iron oxyhydroxide (NiFeOOH) as a cocatalyst of the oxygen evolution reaction (OER) on the Ni foil using a Ni and Fe precursor solution by casting. “This metal-encapsulated FAPbI3 photoanode records a photocurrent density of 22.8 mA cm-2 at 1.23 VRHE and shows excellent stability for 3 days under simulated 1-sun illumination,” they stressed, noting that its performance is comparable to that of photovoltaic devices based on organic and inorganic perovskite metal halide (PSK) materials.
“We optimized this photoanode using different metal foils and studied the catalyst-electrolyte interactions in depth,” Hanshora explained, noting that photoanodes with sizes of 0.25 cm2, 7.68 cm2, 30.8 cm2 and 123.2 cm were built and tested. cm2 in a single reactor system.
Next, the research group built the prototype PEC water splitting system using the photoanode and a platinum (Pt) wire as the cathode. They immersed the anode and cathode in the electrolyte inside the PEC reactor, while installing another FAPbI3 photovoltaic cell outside the electrolyte in a side-by-side parallel connection.
“These scaled, small area photoanodes recorded STH efficiencies of 9.8% (0.25 cm2), 8.9% (7.68 cm2), 8.5% (30.8 cm2), and 8.5% ( 123.2 cm2)”, point out the researchers, who point out that the photoanode was scaled by increasing the size of the unit cell, the number of cells (multicell) and the number of reactors.
“Such results demonstrate the possibility that the high STH efficiency of small cells can be maintained in large cell photoanodes,” they stated, although they also recognized that the efficiency values ??achieved are still insufficient for the practical production of PEC hydrogen.
“We plan to further improve the efficiency and stability of the PEC system by integrating photoelectrodes and selecting a more efficient and durable catalyst,” Hansora said.
The system was presented in the article “ All-perovskite-based unassisted photoelectrochemical water splitting system for efficient, stable and scalable solar hydrogen production ” and scalable), recently published in nature energy . |
