We systematically studied water adsorption and oxidation on the unreconstructed TiO2(001) surface using first-principles calculations.

Genetic algorithm (GA) is a common optimization technique that has two fatal limitations: low convergence speed and premature convergence to the local optimum. As an effective method to solve these drawbacks, an adaptive genetic algorithm (AGA) considering adaptive crossover and mutation operators is proposed in this paper. Verified by two test functions, AGA shows higher convergence speed and stronger ability to search the global optimal solutions than GA. To meet the crashworthiness and lightweight demands of automotive bumper design, CFRP material is employed in the bumper beam instead of traditional aluminum. Then, a multiobjective optimization procedure incorporating AGA and the Kriging surrogate model is developed to find the optimal stacking angle sequence of CFRP. Compared with the conventional aluminum bumper, the optimized CFRP bumper exhibits better crashworthiness and achieves 43.19% weight reduction.

The rutile TiO 2 (011) surface exhibits a (2 × 1) reconstruction when prepared by standard techniques in ultrahigh vacuum. However, the reconstructed surface is incomplete and discussed controversially for understanding the enhanced photoactivity occurred in most photocatalytic experiments. Herein, we investigated the reactivity of unreconstructed TiO 2 (011)-(1 × 1) and reconstructed TiO 2 (011)-(2 × 1) surfaces toward methanol adsorption and oxidation using first-principles calculations. The TiO 2 ( 011)-(1 × 1) surface is preferred energetically over the TiO 2 (011)-(2 × 1) surface at high methanol coverage, confirming that the interaction with methanol leads to an inversion of the stabilities of the reconstructed and unreconstructed surfaces. Then, we intensively investigated methanol oxidation into formaldehyde on the TiO 2 (011)-(1 × 1) surface and found that the methanol oxidation underwent the same pathways as those on the TiO 2 (011)-(2 × 1) and TiO 2 (110) surfaces. By means of the energy barriers of the rate-determining step (i.e., C−H cleavage), it is demonstrated that the unreconstructed TiO 2 (011) surface exhibits higher reactivity toward methanol oxidation than the reconstructed TiO 2 (011) and TiO 2 (110) surfaces. In addition, the calculated density of states further indicate that the TiO 2 (011) surface has stronger oxidative ability than TiO 2 (110) for photocatalysis. Thus, our findings suggest that the synergistic effect of surface atomic and electronic structures may play an important role in the enhanced photocatalytic activity of TiO 2 (011) observed in aqueous environments typical of most photocatalytic application of TiO 2 .

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