光催化量子效率的提高是解决可回收二氧化钛（TiO2）基光催化材料商业应用瓶颈的途径。可回收TiO2基光催化材料主要有块体和“TiO2基/负载”两种形式。但目前这些材料成本高，光催化量子效率低。针对成本问题，本项目拟采用已在前期中取得成功的成本低、工艺简单、可工业化生产的微波法来制备碳、氮掺杂TiO2多孔块体和“碳、氮掺杂多孔TiO2薄膜/金属板”复合材料。而由于光催化量子效率低的主要原因是光生载流子寿命短。申请者提出采用宏观电场取代局域内建场来分离光生电子与空穴，更大幅度提高光生载流子寿命。故本项目探索以下延长光生载流子寿命新机理：（1）通过半导体Seebeck效应产生宏观电荷分离，自发建立宏观电场；（2）块体边缘曲率半径不同造成载流子分布不匀来自发建立宏观电场；（3）选择有合适功函数的金属板作为沉积碳、氮掺杂多孔TiO2薄膜基板，在膜和板之间建立方向一致阻挡层，延长光生载流子寿命。

The recoverable titanium dioxide based photocatalysts could be used commercially only after its quantum efficiency has been upgraded to the commercially-required level. The recoverable titanium dioxide based photocatalysts mainly have two types: titanium dioxide based bulk and “titanium dioxide based film/bulk carrier”, both of which presently have high cost and low quantum photocatalytic efficiency. To solve the high cost problem, a microwave method would be employed to prepare the porous carbon-and-nitrogen co-doped titanium dioxide bulk and porous“carbon-and-nitrogen co-doped titanium dioxide film/metal bulk carrier” (hereafter called “film/plate”) in this proposal. This method is characteristic of low-cost, simplicity, and ability to apply in industry scale. More importantly, this method had been checked in our earlier-stage work to be successful in producing pores in bulk and depositing carbon-and-nitrogen co-doped titanium dioxide film on a bulk carrier. On the other hand, the low quantum efficiency arises mainly from short carriers’ lifetime. The applicants think that a macroscopic electric filed is more advantageous than a local internal electrical field in longer carriers’ lifetime. Therefore, in this work, on the above-said prepared samples, the following new mechanism which prolong the lifetime of photo-produced electrons and holes will be explored: (1) by producing a temperature step in the either ends of carbon-and-nitrogen co-doped titanium dioxide porous bulk, a macroscopic electric filed would be produced owing to the Seebeck effect; (2) by producing different bulk edge curvature radii, an inhomogeneous charge distribution in the carbon-and-nitrogen co-doped titanium dioxide porous bulk, therefore, a macroscopic electric field would occur; (3) by depositing porous carbon-and-nitrogen co-doped titanium dioxide film on the metal plate which has suitable work function resulting in producing a “hindering layer” in the “porous film/plate” , a unanimously direction of electric field perpendicular to the metal plane would be occur. This kind of electric field would separate the photo-produced holes and electrons in more amount. Therefore, a longer photo-produced carriers’ lifetime would be obtained.