Advancements in p-type zinc oxide for photocatalytic water splitting
Advancements in p-type zinc oxide for photocatalytic water splitting lead image
Photocatalytic water splitting is a promising technology to produce clean and renewable energy without pollutant byproducts. The process involves the dissociation of water into hydrogen and oxygen using light. Cao et al. summarized the preparation and application of p-type zinc oxide (ZnO), a photocatalytic material that has superior properties for photocatalytic water splitting.
“The process of high-efficiency ZnO-based optoelectronic systems for industrial production is still limited, mainly because the formation of stable p-n ZnO junctions is essential,” said author Shiwei Lin. “In general, the prepared ZnO often exhibits natural n-type characteristics. Therefore, it is highly desired to focus more attention on constructing p-type ZnO, which can provide more possibilities for boosting the photocatalytic water splitting system.”
Doping to prepare p-type ZnO nanostructures is one possible approach to enhance the performance of photocatalytic water splitting. Various synthetic techniques — such as doping group-I elements into Zn sites, doping group-V elements, and co-doping group III and V elements into ZnO — can introduce new energy levels in the band gap of ZnO. This extends the light adsorption from the UV region to visible light wavelengths.
However, not all band engineering via doping can generate proper and effective new energy levels to form p-type ZnO. Instead, it may create new charge recombination centers that reduce photocatalytic performance.
“The biggest challenge for water splitting is the stability of as-prepared p-type ZnO, which nowadays is very poor compared to n-type ZnO,” said Lin. “In most of the previous reports, p-type ZnO only kept stable within 1 year under ordinary storage conditions while the longest time was about 2 years.”
Source: “p-type ZnO for photocatalytic water splitting,” by Chang Cao, Bingqing Zhang, and Shiwei Lin, APL Materials (2022). The article can be accessed at http://doi.org/10.1063/5.0083753 .
