Liquid Phase Plasma-TiO₂（B） Catalysis For H₂O₂ Evolution

Low energy consumption and"green"preparation of hydrogen peroxide（H₂O₂）is an im-portant subject under the two-carbon strategy.Liquid phase plasma discharge can use clean electric energy,water and air as raw materials,safe,"green",on-site preparation of H₂O₂,which is a promising technology to replace the traditional anthraquinone method with high energy consumption.However,the life span of the active species produced by plasma is short and the reaction mechanism is complex,which leads to the low yield of H₂O₂ prepared by plasma dis-charge.Therefore,this paper focuses on the coupling strategy between catalyst and liquid plasma discharge,in order to improve the conversion rate of reactants and the selectivity of required products,and achieve high energy efficiency and green dispersed preparation of H₂O₂.By coupling highly crystalline TiO₂（B）nanowires with liquid plasma,the synergism mecha-nism of the high crystalline TiO₂（B）nanowires on the formation of liquid plasma H₂O₂ was investigated.Carbon modified TiO₂（B）nanowires were further constructed to broaden the op-tical absorption range of the catalyst,optimize the desorption performance of H₂O₂,and further improve the selectivity of H₂O₂,so as to explore a new feasibility for the preparation of H₂O₂.The main research contents are as follows:（1）Study on the performance of H₂O₂ production by TiO₂（B）nanowires coupled with liq-uid plasma:TiO₂（B）nanowires with ultra-high crystallinity were successfully prepared by melt-ing salt-hydrothermal two-step method.Excellent crystalline metastable phase TiO₂（B）has sta-ble physical and chemical structure and strong photocarrier separation ability.The performance of TiO₂（B）nanowire-coupled liquid plasma discharge for preparation of H₂O₂ shows that the introduction of catalyst can effectively improve the generation rate of H₂O₂.The production of H₂O₂ in the TiO₂（B）nanowire-coupled discharge system with the best crystallinity is the highest,which increases by 696.8μmol/L/h compared with the system without catalyst.The existence of catalyst significantly changes the discharge form,the energy generated by plasma becomes stronger,the discharge area is widened,more oxygen active substance（·OH）is excited,and the reactivity in the system is improved.Meanwhile,compared with other crystalline TiO₂,the fast diffusion behavior of H₂O₂ on TiO₂（B）（001）crystal plane effectively inhibits the re-decompo-sition of H₂O₂ on the catalyst surface,thus further improving the production efficiency of H₂O₂.（2）The performance of TiO₂（B）@C composite catalyst coupled with liquid plasma to pro-duce H₂O₂:Using glucose as carbon source,amorphous carbon and TiO₂（B）nanowires com-posite material（TiO₂@C）was successfully prepared by a simple one-step hydrothermal method.Compared with TiO₂（B）,the optical absorption range of the composite is expanded from the ultraviolet region to the visible region,which improves the optical utilization rate and signifi-cantly enhances the transfer ability of photogenerated electrons.The performance of TiO₂（B）@C composite catalyst coupled with liquid plasma to produce H₂O₂ showed that the total output of TiO₂（B）@C coupled discharge system increased by 181μmol/L in 1 h compared with the original sample.The control experiment showed that amorphous carbon modification could also increase the catalytic performance of other crystalline phases（anatase,rutile）TiO₂to produce H₂O₂,which proved that the carbon modification catalyst has the applicability to promote the synthesis of H₂O₂.The mechanism analysis showed that TiO₂@C catalyst had sig-nificant effects on the plasma intensity,solution composition and concentration of active spe-cies,and showed better catalytic activity under UV light.In addition,amorphous carbon can delay the re-consumption of H₂O₂ by inhibiting the adsorption of H₂O₂ on the surface of TiO₂nanoparticles,thus increasing the total production of H₂O₂ in the plasma-catalytic system and in the catalytic system.