An environment-benign method for the synthesis of p-NiO/n-ZnO heterostructure with excellent performance for gas sensing and photocatalysis

NiO-wrapped mesoporous TiO2 microspheres based selective ammonia sensor at room temperature

“…Among the methods to improve the selectivity of the metal oxide based gas sensors, additives of the oxides with opposite conduction type showed more promising [1,[20][21][22][23]. That is, for n-type metal oxides, the addition of p-type ones has been found to be able to enhance the sensitivity and as well the selectivity of gas sensors.…”

“…That is, for n-type metal oxides, the addition of p-type ones has been found to be able to enhance the sensitivity and as well the selectivity of gas sensors. One possible reason could be due to the p-n junction where the depletion layer was further excavated leading to a higher change in the resistance when exposed to the gas analytes although the catalytic roles played by the additive p-type oxides might also be a factor for the enhancement [1,[20][21][22][23]. P-type NiO has often been studied for such role because of its one more attractive property: stronger oxygen and water absorbents [1,21].…”

“…P-type NiO has often been studied for such role because of its one more attractive property: stronger oxygen and water absorbents [1,21]. With stronger oxygen adsorption ability, the NiO would attract more oxygen ionized at the surface trapping more electrons from the surface of the oxide and consequently further deepen the depletion layer formed at p-n junction thus enhancing the sensor response [1,[20][21][22][23]. Meanwhile, the excellent water absorbing capacity of NiO has been found to protect the bulky n-type oxide from humidity influence leading to a better humidity-resistant response of the sensor [1].…”

UV photo-detector based on p-NiO thin film/n-ZnO nanorods heterojunction prepared by a simple process

“…On the other hand, nickel oxide (NiO) has been under investigation for different technological applications due to its wide direct band gap (3.6 -4.0 eV) and it is intrinsically p type semiconductor. These properties make NiO a suitable candidate for the fabrication of pNiO/n-ZnO heterojunction based UV photo-detectors [15][16][17][18]. Alternative inexpensive fabrication techniques are usually needed to realize large scale, mass production and low cost UV photo-detectors with high performance.…”

Effect of NiO intermediate layer on the optical and electrical properties of n-ZnO nanorods/p-GaAs heterojunction

“…The efficiency of ZnO homojunctions has been limited due to the low carrier concentration, instability and low mobility of the holes in ZnO [7,8]. So, the growth of n-ZnO nanostructures on other p-type semiconductors such as Si [9], GaN [10][11][12], SiC [13][14][15][16] and NiO [17][18][19] can provide alternative way to realize ZnO-based p-n heterojunctions. To the best of our knowledge, few researchers have used p-GaAs as a substrate for ZnO-based LEDs [20,21], and there have been no detailed investigations reported about use of an intermediate layer to improve the optical and electrical properties of n-ZnO nanorods/p-GaAs heterojunction.…”