Here, a photoelectrochemical (PEC) photodetector with good flexibility and high photoresponsivity was successfully fabricated in a vertical structure, where the MXene (Ti2CTx) nanosheet and carbon black electrode were separated by adenosine triphosphate/nicotinamide adenine dinucleotide phosphate (ATP/NADPH)-incorporated solid-state electrolyte. The photocurrent and photoresponsivity can reach 1.84 μA/cm2 and 8.89 μA/W, respectively, under a light intensity of 90 mW/cm2 at a bias potential of 0.6 V, which are approximately 2.3 times those of Ti2CTx nanosheets. The addition of ATP and NADPH to the electrolyte also leads to a large decrease of the rise time from 0.76 to 0.26 s. Furthermore, the photodetector can continue to function and maintain stability under 45° bending and after 500 cycles of bending, indicating a robust device structure and great flexibility. The performance enhancement of the PEC photodetector can be attributed to the synergistic effect of electrolyte additives on Ti2CTx nanosheets, where ATP and NADPH greatly enhance the circulation and utilization of photogenerated carriers. This work suggests that the incorporation of chloroplast-inspired carrier circulation with two-dimensional nanosheets could achieve efficient light-current conversion, providing a new strategy to improve the performance of PEC-type photodetectors.
MXenes have demonstrated exceptional potential in the adsorption of uranium (U(VI)) from wastewater. However, significant challenges remain in the investigation of its adsorption capacity and mechanism. To enhance the adsorption capacity of Ti 2 CT x , this study conducted alkalization experiments on Ti 2 CT x and subsequently prepared Ti 2 C(OH) 0.13 @SA aerogel spheres by combining alkalized Ti 2 C(OH) 0.13 with sodium alginate (SA). The results indicated that alkalization effectively increased the proportion of OH functional groups. After alkalization treatment, Ti 2 C(OH) 0.13 exhibits a significantly enhanced adsorption capacity, reaching up to 951 mg g −1 , which represents more than a twofold increase compared with untreated Ti 2 CT x . The adsorption follows pseudo-second-order kinetics and the Langmuir isotherm model, suggesting chemical and monolayer adsorption, respectively. Thermodynamic studies reveal an endothermic adsorption process. DFT calculations demonstrate that the OH functional group forms chemical bonds with U(VI), promoting reductive adsorption. Aside from electrostatic adsorption, XPS analysis confirms Ti(II) oxidation and U(VI) reduction. This study further investigates the adsorption capacity of Ti 2 C(OH) 0.13 @SA aerogel spheres in simulated seawater environments. It is found that even at an ultra-low concentration of U(VI) as low as 3.3 μg/L, these aerogel spheres still exhibit significant adsorption performance, with an adsorption capacity reaching up to 3.21 mg g −1 , highlighting their substantial potential for applications.
Hydrogels are excellent stretchable engineering materials composed of polymers, which are widely studied as flexible conductors in smart, flexible devices. However, hydrogels have only been studied for their electrical conductivity, which hinders their further application in optoelectronic devices. Herein, a hydrogel photoelectrochemical (PEC) photodetector by using polyvinyl alcohol (PVA) hydrogel as an electrolyte carrier and further embedding Ti 2 CT x nanosheets in the hydrogel is presented. Under a bias potential of 0.6 V and a light intensity of 60 mV cm −2 , the photodetector exhibited a photocurrent density of 0.178 μA cm −2 and a responsivity of 2.96 μA W −1 . Furthermore, due to the structure of the special nanosheets network of hydrogel photodetectors, the photodetector maintained stable properties even after 1500 cycles of stretching at 100% strain and 50 cycles of cutting-off the self-healing cycle, this indicates that the prepared hydrogel photodetector is a high-quality stretchable, self-healing device. This study provides a novel approach for hydrogel functionalization and widens the design horizons and potential applications of photodetectors.
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