Photocatalytic hydrogen production from seawater under full solar spectrum without sacrificial reagents using TiO_(2) nanoparticles

Photocatalytic water splitting(PWS)has attracted widespread attention as a sustainable method for converting solar to green hydrogen energy.So far PWS research has mainly focused on the development of artificial photocatalytic hydrogen production systems for pure water.It is more practically attractive to create systems for seawater,i.e.,to reduce the cost of hydrogen production and make better use of naturally occurring water resources.Herein,brookite,anatase,and rutile TiO_(2)nanoparticles are investigated as photocatalysts to explore the feasibility of such thought and have shown attractive hydrogen production performance under full solar spectrum without any sacrificial agent.It is worth noting that,brookite TiO_(2),has more suitable band gap position and excellent photoelectric properties compared with anatase and rutile TiO_(2),and has higher efficiency and stability in the process of hydrogen production.The photocatalytic hydrogen production rate of brookite TiO_(2)can reach up to 1,476μmol/g/h,the highest value reported for TiO_(2)-based systems and most other photocatalysts in seawater splitting under full spectrum.As the Cl−ions in seawater go through a cycle of oxidation and reduction,no Cl_(2) is detected in the solar hydrogen production from seawater.

Combined effects of adsorption and photocatalysis by hybrid TiO_2/ZnO-calcium alginate beads for the removal of copper

The use of nanosized titanium dioxide（TiO2） and zinc oxide（ZnO） in the suspension form during treatment makes the recovering and recycling of photocatalysts difficult.Hence,supported photocatalysts are preferred for practical water treatment applications.This study was conducted to investigate the efficiency of calcium alginate（CaAlg） beads that were immobilized with hybrid photocatalysts,TiO2/ZnO to form TiO2/ZnO-CaAlg.These immobilized beads,with three different mass ratios of TiO2：ZnO（1：1,1：2,and 2：1） were used to remove Cu（Ⅱ） in aqueous solutions in the presence of ultraviolet light.These beads were subjected to three cycles of photocatalytic treatment with different initial Cu（Ⅱ） concentrations（10-80 ppm）.EDX spectra have confirmed the inclusion of Ti and Zn on the surface of the CaAlg beads.Meanwhile,the surface morphology of the beads as determined using SEM,has indicated differences of before and after the photocatalytic treatment of Cu（Ⅱ）.Among all three,the equivalent mass ratio TiO2/ZnO-CaAlg beads have shown the best performance in removing Cu（Ⅱ） during all three recycling experiments.Those TiO2/ZnO-CaAlg beads have also shown consistent removal of Cu,ranging from 7.14-52.0 ppm（first cycle） for initial concentrations of10-80 ppm.In comparison,bare CaAlg was only able to remove 6.9-48 ppm of similar initial Cu concentrations.Thus,the potential use of TiO2/ZnO-CaAlg beads as environmentally friendly composite material can be further extended for heavy metal removal from contaminated water.