Research On Photoelectrocatalytic Hydrogen Production Performance Of TiO₂ Film Electrode Based On Hydrogen Sensing Fiber Bragg Grating

Energy is an important material basis affecting the national economy and social system,and a key factor affecting the national development right and core competitiveness.Hydrogen energy has become an ideal form of energy supply because of its extensive sources,high calorific value,clean and pollution-free characteristics.The process of hydrogen production by photoelectrocatalytic water-splitting technology is clean,pollution-free and by-product free,which is a potential way of hydrogen production.Hydrogen is the main product of photoelectrocatalytic hydrogen production system.In order to understand the mechanism of hydrogen production and optimize the process control,on-line in-situ monitoring of hydrogen concentration and distribution in the process of Photoelectrocatalytic hydrogen production is particularly important.However,there is no on-line in-situ detection method for hydrogen concentration on the electrode surface and the surrounding liquid space of the closed photoelectrocatalytic hydrogen production reactor,and the performance of the existing optical fiber hydrogen sensor is easily affected by the environmental temperature and humidity.Based on this,a kind of hydrogen sensing fiber Bragg grating sensor with variable temperature and high humidity was developed,and then the TiO₂ nanotube array photoelectric anode material was prepared,and its performance was characterized.Finally,a TiO₂ film electrode photocatalytic hydrogen production reactor and its on-line monitoring system were built to explore the mechanism and law of photocatalytic hydrogen production process.The main results are as follows.(1)In this paper,a new fabrication method of FBG hydrogen sensor based on chemical plating assisted by polydopamine is proposed.The influence of variable temperature and high humidity environment on the hydrogen sensing response of FBG sensor is further eliminated by using silicon oxide superhydrophobic coating and temperature compensation grating.The experimental results show that hydrazine hydrate as reducing agent is more suitable for Pd electroless plating technology assisted by polydopamine.The prepared Pd film is compact and uniform without cracks.The Pd film prepared by sodium hypophosphite as reducing agent is easy to crack and has poor hydrogen sensing response performance.When the thickness of polydopamine coating is8.9 nm,the thickness of Pd electroless plating by hydrazine hydrate is 130.7 nm The FBG hydrogen sensor has high sensitivity and fast response time when coated with 15 layers of Si O2 hydrophobic film.The sensor can stably and accurately respond to the change of hydrogen concentration in the temperature range of 30-70?and humidity range of20-90%RH,with a sensitivity of 10.80 pm/%and a relative error of less than 7.2%.(2)SEM images of TiO₂ nanotube films prepared by anodic oxidation method show that the TiO₂ nanotube films show uniform orientation nanotube arrays,uniform orifice diameter and no cracks.The diameter of the orifice is about 100 nm and the thickness of the film is about 4?m.XRD and XPS analysis show that the TiO₂ nanotube material is composed of Ti and O,which conforms to the diffraction characteristic peak of anatase TiO₂ and has good light absorption ability.The photoelectrochemical properties test results show that the TiO₂ nanotube photoanode has high photoelectric response ability,and the photocurrent reaches 1.1 m A/cm².(3)The fiber Bragg grating sensor array constructed in this paper can accurately and effectively monitor the hydrogen concentration and temperature change information in the electrode interface and nearby solution in the reactor cathode chamber.It was found that the temperature in the cathode chamber of the reactor first increased and then stabilized after 6000 s.The hydrogen sensing fiber on the electrode surface shows that the concentration of supersaturated dissolved hydrogen reaches a peak at 141 s,and then decreases to a stable value.