Oxygen vacancies (OVs) are a mixed blessing for the photoelectrochemical (PEC) water oxidation performance of monoclinic tungsten trioxide (m-WO 3 ) photoanodes. Although it is widely accepted that a moderate concentration of OVs is beneficial for the PEC performance of the m-WO 3 photoanodes, this argument assumes a uniform distribution of OVs throughout the m-WO 3 crystal. In this case, only the overall concentration of OVs needs to be considered. However, the spatial non-uniformity of OV defects in m-WO 3 photoanodes has not been thoroughly examined. In this study, by employing a m-WO 3 nanorod array as a model photoanode, the aim is to show that a higher OV concentration near the surface of m-WO 3 compared to that in the bulk is advantageous for the PEC performances of this material. In addition, a laser-assisted defect control (LADC) process is employed to manipulate the spatial distribution of OVs in the m-WO 3 photoanodes to achieve enhanced PEC performances. Moreover, a one-step laser deposition process is introduced to obtain an ultrathin FeNi oxygen evolution catalyst overlayer on the defect-controlled m-WO 3 photoanodes, further improving PEC performance, photostability, and Faradaic efficiency.

UV micro-photodetectors (mPDs) have received significant attention owing to the increasing demand for application in wearable healthcare devices. However, mPDs often suffer from tiny signals owing to their small size. Although this problem can be overcome by using low-dimensional nanomaterials with high surface-to-volume ratios, such as nanowires (NWs), selective synthesis of functional NWs on the desired position of the specific substrate is challenging. This study introduces, for the first time, the laserinduced hydrothermal growth (LIHG) process, in which a strongly focused laser beam generates a localized high-temperature field, enabling the localized growth of CuO NWs on the desired position of the specific substrate. Also, an all-laser direct patterning process for the fabrication of a flexible mPD based on a p-CuO NW/n-ZnO NW heterojunction is demonstrated. The PN NWs heterojunction exhibits remarkable photocurrent enhancement compared to a homojunction with a single semiconductor material. Furthermore, the all-laser direct patterning process of the flexible PN NWs heterojunction can be applied for the fabrication of other flexible optoelectronic applications.

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