The surface electron density significantly affects the photocatalytic efficiency, especially the photocatalytic CO2 reduction reaction, which involves multi-electron participation in the conversion process. Herein, we propose a conceptually different mechanism for surface electron density modulation based on the model of Au anchored CdS. We firstly manipulate the direction of electron transfer by regulating the vacancy types of CdS. When electrons accumulate on vacancies instead of single Au atoms, the adsorption types of CO2 change from physical adsorption to chemical adsorption. More importantly, the surface electron density is manipulated by controlling the size of Au nanostructures. When Au nanoclusters downsize to single Au atoms, the strong hybridization of Au 5d and S 2p orbits accelerates the photo-electrons transfer onto the surface, resulting in more electrons available for CO2 reduction. As a result, the product generation rate of AuSA/Cd1−xS manifests a remarkable at least 113-fold enhancement compared with pristine Cd1−xS.

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Single‐atom catalysts (SACs) have attracted great attention owing to their maximum atomic utilization and high catalytic performance in electrochemical reactions. But the synthesis of SACs is not easy due to large surface energies of single atomic metal sites which often lead to their aggregation. The defects on supports can serve as anchor sites to stabilize single metal atoms and prevent them from aggregation, which has become an effective method to fabricate SACs. This review summarizes the meaningful findings about the defects on supports stabilizing single metal atoms, and their applications in electrocatalytic reaction. Various defects, including the intrinsic defects or heteroatom doping of carbon‐based materials, cation or anion vacancies of metal compound supports, and other defects (step edges, lattice defects, and caves), are comprehensively summarized, and the effects of defects on designing SACs are discussed. Although there are still many challenges to fully explore the SACs, it is believed that the newly established defect sites stabilized single atoms mechanism will be helpful for designing and fabricating highly powerful single atomic electrocatalysts for practical applications.

To optimize the field emission behavior of the ZnO nanorods, postthermal annealing in different ambience was conducted. The field emission properties of the ZnO nanorods are considerably improved after annealing in oxygen and getting worse when annealing in air or ammonia. Photoluminescence and Raman spectroscopy were employed to elucidate the reason for such a significant improvement of the field emission when annealing in oxygen. Those detailed analyses suggested that oxygen annealing can reduce the oxygen vacancy concentration, improve the crystal quality, lower the work function, and increase the conductivity of the ZnO nanorods. Our work is important for applications of ZnO nanorods as a promising candidate in flat panel displays and high brightness electron sources.

This contribution deals with problems related to the parity relation-based residual generation. A characterization of parity vectors and a relationship between the order of parity relations and the dimension of the parity space are derived. The achieved results are used to determine the degree of freedom for designing parity relation-based residual generators and to study the robustness problem.