Among numerous efforts toward preparation of visible-light TiO.sub.2, recently design and control for chemical structure of TiO.sub.2 outermost surface have been paid strong attention to enhance photocatalytic performance. We have previously succeeded in direct synthesis of structurally well-controlled TiO.sub.2 with highly concentrated Ti.sup.3+ from metal titanium particle via single-mode magnetic microwave (SMMW)-assisted reactions. Here, we demonstrate synthesis of Ti.sup.3+ and interstitial nitrogen (N.sub.int) co-doped TiO.sub.2 in Ar/O.sub.2/N.sub.2 system during one-step SMMW-assisted reactions, where chemical structure of outermost surface is rigorously controlled. In addition, such one-step-generated TiO.sub.2 shows significant thermal stability which has not been achieved in previously reported deficient TiO.sub.2 even through several step reactions. Additionally, the synthesized co-doped TiO.sub.2 with specific surface structures shows superior visible-light photocatalytic performance for photo-degradation of rhodamine B. The mechanism of outermost surface formation is systematically investigated by characterizations of XRD, XPS, UV-Vis absorption and PL. It demonstrates that the specific TiO.sub.2 surface including highly concentrated Ti.sup.3+ and N.sub.int can be attributed to the rapid heat-dynamics during the reaction, which enhance the efficiency for separation of photo-excited carriers. The one-step SMMW-assisted reactions on metallic particle as bottom-up process will open new strategy for material design of functional metal oxides.