Photocatalytic Activity of Toluene under UV-LED Light with TiO₂Thin Films

Abstract

Titanium dioxide (TiO<sub >2</sub>) and ferric-doped TiO<sub >2</sub> (Fe-TiO<sub >2</sub>) thin films were synthesized on the surface of 304 stainless steel sheets using a simplified sol-gel preparation method. The Fe-TiO<sub >2</sub> thin films were prepared with weight-to-volume ratios of <svg style="vertical-align:-0.16379pt;width:29.3375px;" id="M1" height="16.049999" version="1.1" viewBox="0 0 29.3375 16.049999" width="29.3375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,15.775)"><path id="x46" d="M493 503l-29 -4q-13 56 -28 80q-13 22 -35.5 29.5t-78.5 7.5h-76q-22 0 -27.5 -5t-5.5 -27v-238h103q66 0 82.5 12t25.5 62h29v-193h-29q-9 54 -25.5 67t-82.5 13h-103v-181q0 -64 15 -78.5t84 -19.5v-28h-272v28q61 5 74.5 19.5t13.5 78.5v399q0 64 -13 78t-72 19v28&#xA;h440q1 -40 10 -147z" /></g><g transform="matrix(.017,-0,0,-.017,8.732,15.775)"><path id="x65" d="M380 106l15 -22q-42 -52 -87 -74t-76 -22q-89 0 -142 62t-53 151q0 103 66 175q67 73 146 73h1q61 0 105.5 -46.5t44.5 -105.5q0 -16 -4.5 -22.5t-18.5 -9.5q-54 -10 -262 -17q1 -95 46 -143.5t104 -48.5q61 0 115 50zM225 412q-35 0 -64.5 -32.5t-40.5 -90.5q83 0 170 3&#xA;q14 0 19 4.5t5 15.5q1 41 -23.5 70.5t-65.5 29.5z" /></g> <g transform="matrix(.012,-0,0,-.012,15.95,7.613)"><path id="x33" d="M285 378v-2q65 -13 102 -54.5t37 -97.5q0 -57 -30.5 -104.5t-74 -75t-85.5 -42t-72 -14.5q-31 0 -59.5 11t-40.5 23q-19 18 -16 36q1 16 23 33q13 10 24 0q58 -51 124 -51q55 0 88 40t33 112q0 64 -39 96.5t-88 32.5q-29 0 -64 -11l-6 29q77 25 118 57.5t41 84.5&#xA;q0 45 -26.5 69.5t-68.5 24.5q-67 0 -120 -79l-20 20l43 63q51 56 127 56h1q66 0 107 -37t41 -95q0 -42 -31 -71q-22 -23 -68 -54z" /></g><g transform="matrix(.012,-0,0,-.012,21.661,7.613)"><path id="x2B" d="M535 230h-212v-233h-58v233h-213v50h213v210h58v-210h212v-50z" /></g> </svg>/TiO<sub >2</sub> of 0.3&#x25;, 0.5&#x25;, and 0.7&#x25;, respectively. The crystalline phase structures of the prepared TiO<sub >2</sub> and Fe-TiO<sub >2</sub> thin films were entirely anatase. The measured optical band gaps of the TiO<sub >2</sub>, 0.3&#x25; Fe-TiO<sub >2</sub>, 0.5&#x25; Fe-TiO<sub >2</sub>, and 0.7&#x25; Fe-TiO<sub >2</sub> thin films were 3.27, 3.28, 3.22, and 2.82&#x2009;eV, respectively. The grain sizes and other physical properties of the prepared thin films were also reported. 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An increase in <svg style="vertical-align:-0.16379pt;width:29.3375px;" id="M8" height="16.049999" version="1.1" viewBox="0 0 29.3375 16.049999" width="29.3375" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(.017,-0,0,-.017,.062,15.775)"><use xlink:href="#x46"/></g><g transform="matrix(.017,-0,0,-.017,8.732,15.775)"><use xlink:href="#x65"/></g> <g transform="matrix(.012,-0,0,-.012,15.95,7.613)"><use xlink:href="#x33"/></g><g transform="matrix(.012,-0,0,-.012,21.661,7.613)"><use xlink:href="#x2B"/></g> </svg> dopant concentration could enhance the photocatalytic activity of toluene decomposition as a result of lower optical band gaps, smaller grain size, and higher surface area.