プルシアンブルー担持酸化タングステンのアセトアルデヒド分解反応における光触媒性能

摘要

We prepared a new visible light-responsive photocatalyst, tungsten oxide, supported with Prussian blue (PB-WO_3) by a kneading method. The photocatalytic performance of PB-WO_3 was improved to photodegrade acetaldehyde completely under visible light. We investigated the formation rate constant of carbon dioxide (CO_2) generated by the photodegradation of acetaldehyde, in order to compare the photocatalytic performance of PB-WO_3 to that of tungsten oxide supported with copper oxide (CuO-WO_3)， which was reported previously. As a result, the formation rate constant of CO_2 in PB-WO_3 indicated 2.1×10~(-2) min~(-1), which was nearly twice as much as that in CuO-WO_3. When we investigated the PB-WO_3 after completion of the photodegradation of acetaldehyde to find a factor for the improvement of the photocatalytic performance of PB-WO_3, decoloration was observed. It was caused by the reduction of PB by exited electron. It was suggested that the oxidation reaction proceeded effectively on a positive hole, because the reduced PB supported on WO_3 prevented recombination of the excited electron. Also, the photocatalytic durability of PB-WO_3 was better than that of CuO-WO_3, which was evaluated based on the decrease of the formation rate constants of CO_2 by repeating the photodegradation of acetaldehyde.%乾式混練することにより酸化タングステン(WO_3)上へプルシアンブルー(PB)を担持し，新しい可視光応答型光触媒(PB-WO_3)を作製した.PBを担持することでWO_3の光触媒活性が向上し，可視光照射下でアセトアルデヒドが完全分解できた.既知の酸化銅担持酸化タングステン(CuO-WO_3)とPB-WO_3の光触媒性能を比較するため，アセトアルデヒド分解反応時に発生する二酸化炭素の生成反応速度定数を調べた.その結果，PB-WO_3を用いた場合の速度定数は2.1×10~(-2)min~(-1)であり，CuO-WO_3を用いた場合の約2倍の値であった.光触媒性能向上の要因を探るためにアセトアルデヒド分解反応直後のPB-WO_3を調べたところ，PBが励起電子により還元されたことによる退色が観察された.よって，WO_3表面に担持したPBが還元されることにより，WO_3内での励起電子と正孔の再結合が防止され，正孔での酸化反応が効率良く進行したと考えられる.またアセトアルデヒド分解反応を繰り返して光触媒性能を評価した結果，PB-WO_3がCuO-WO_3よりも性能の低下が少なく，優れた光触媒耐久性を有することが分かった.