Beihang University

About: Beihang University is a education organization based out in Beijing, China. It is known for research contribution in the topics: Control theory & Microstructure. The organization has 67002 authors who have published 73507 publications receiving 975691 citations. The organization is also known as: Beijing University of Aeronautics and Astronautics.

MXene: a promising photocatalyst for water splitting

Abstract: Identifying suitable photocatalysts for photocatalytic water splitting to produce hydrogen fuel via sunlight is an arduous task by the traditional trial-and-error method. Thanks to the progress of density functional theory, one can nowadays accelerate the process of finding candidate photocatalysts. In this work, by ab initio calculations, we investigated 48 two-dimensional (2D) transition metal carbides also referred to as MXenes to understand their photocatalytic properties. Our results highlight 2D Zr2CO2 and Hf2CO2 as the candidate single photocatalysts for possible high efficiency photocatalytic water splitting. A significant property of 2D Zr2CO2 and Hf2CO2 is that they exhibit unexpectedly high and directionally anisotropic carrier mobility, which may effectively facilitate the migration and separation of photogenerated electron–hole pairs. Meanwhile, these two MXenes also exhibit very good optical absorption performance in the wavelength ranging approximately from 300 to 500 nm. The stability of 2D Zr2CO2 and Hf2CO2 in liquid water is expected to be good based on ab initio molecular dynamics simulations. Finally, the adsorption and decomposition of water molecules on the 2D Zr2CO2 surface and the subsequent formation process of hydrogen were studied, which contributes to the unravelling of the micro-mechanism of photocatalytic hydrogen production on MXenes. Our findings will open a new way to facilitate the discovery and application of MXenes for photocatalytic water splitting.

Distributed robust finite-time nonlinear consensus protocols for multi-agent systems

Abstract: This paper investigates the robust finite-time consensus problem of multi-agent systems in networks with undirected topology. Global nonlinear consensus protocols augmented with a variable structure are constructed with the aid of Lyapunov functions for each single-integrator agent dynamics in the presence of external disturbances. In particular, it is shown that the finite settling time of the proposed general framework for robust consensus design is upper bounded for any initial condition. This makes it possible for network consensus problems to design and estimate the convergence time offline for a multi-agent team with a given undirected information flow. Finally, simulation results are presented to demonstrate the performance and effectiveness of our finite-time protocols.