Signal amplification strategies are of great interest in photoelectrochemical (PEC) sensing research. Herein, we explored a novel approach whereby hole transfer was accelerated from the photosensitive material Blue-TiO₂ (B-TiO₂) to the hole mediator N-hydroxyphthalimide (NHPI). Simultaneously, the introduction of the organic molecule NHPI can promote the efficiency of visible light absorption and expand the absorption range of B-TiO₂. Under visible light irradiation, the photocurrent value of NHPI/B-TiO₂ is 2.7-fold larger than that of B-TiO₂, which can be ascribed to the acceleration of hole transfer by NHPI. More specifically, NHPI acts as a hole mediator, which effectively transfers photo-generated holes from the valence band (VB) of B-TiO₂ to NHPI. NHPI can be oxidized to phthalimide-N-oxyl radical (PINO*), thereby causing inhibition of photo-generated carrier recombination and enhancement of the photocurrent. Furthermore, a PEC aptasensor for the sensitive detection of diazinon (DIA) was constructed by combining specific aptamers on an NHPI/B-TiO₂ nanocomposite surface. The oxidation product of NHPI, PINO*, oxidizes the DIA captured by the aptamer. Under optimized experimental conditions, the linear range for DIA detection was 0.1–1000 nM, and the detection limit of the NHPI/B-TiO₂ nanocomposite aptamer sensing was 0.03 nM (S/N = 3). Therefore, this proposed method involving the hole mediator can be used as a new strategy to improve the performance of PEC.

信号放大策略在光电化学 (PEC) 传感研究中具有重要意义。在此，我们探索了一种新的方法，通过该方法可以加速从光敏材料 Blue-TiO ₂ (B-TiO ₂ ) 到空穴介质 N-羟基邻苯二甲酰亚胺 (NHPI) 的空穴转移。同时，有机分子NHPI的引入可以提高可见光吸收效率，扩大B-TiO ₂的吸收范围。在可见光照射下，NHPI/B-TiO 2 的光电流值是B-TiO _2的2.7倍，这可以归因于 NHPI 对空穴传输的加速。更具体地说，NHPI充当空穴介体，其有效地将光生空穴从B-TiO ₂的价带(VB)转移到NHPI。NHPI可被氧化为邻苯二甲酰亚胺-N-氧基自由基（PINO*），从而抑制光生载流子复合并增强光电流。_{此外，通过在 NHPI/B-TiO 2}纳米复合材料表面上结合特定的适体，构建了一种用于灵敏检测二嗪农 (DIA) 的 PEC 适体传感器。NHPI 的氧化产物 PINO* 会氧化适配体捕获的 DIA。在优化的实验条件下，DIA检测的线性范围为0.1~1000 nM，NHPI/B-TiO _{2的检测限为}纳米复合适体传感为 0.03 nM (S/N = 3)。因此，这种涉及空穴介体的方法可以用作提高 PEC 性能的新策略。