Cu vacancies enhanced photoelectrochemical activity of metal-organic gel-derived CuO for the detection of l-cysteine

Defect engineering in the photoelectrochemical (PEC) process of photoelectrodes has been extensively studied. But insufficient attention has been received about the impact of metal vacancies (V M ) in PEC process. Herein, the influence of Cu vacancies (V Cu ) on PEC performance of copper oxide (CuO) derived from Cu-based metal-organic gel (Cu-MOG) precursor was reported. It can be found that the presence of more V Cu can improve the PEC activity of CuO photocathode by facilitating the charge separation and transfer. Moreover, the as-prepared CuO was presented as a new PEC sensor to detect l -cysteine (L-Cys) on the basis of the excellent PEC performance, which showed high sensitivity and selectivity. Good linear response of L-Cys within the range of 0.1–6 μM was performed with a detection limit of 0.04 μM. This work not only provides insights into the role of V M in the PEC process of photocathodes, but also proved the high potential applicability of CuO as a PEC device for biomolecule detection.