Hydrogen production by water splitting using a particular photocatalyst has received extensive attention as a substitute for clean energy sources. The efficiency of water splitting strongly relies on the structural and electronic properties of the photocatalyst. In this study, the electronic and optical properties of ZnO/WSe₂ heterobilayers were studied using the first-principles calculations. It is found that the direct band gap was spatially separated for the WSe₂ and ZnO monolayers, forming a van der Waals (vdW) heterostructure with type-II alignment with electrons and holes. The charge transfer from ZnO to WSe₂ resulted in a built-in electric field, improving the photocatalytic efficiency due to a better charge separation. The heterobilayers possessed a small carrier effective mass with high carrier mobility. The valence and conduction bands of the heterostructure perfectly engulfed the redox potentials of water. The heterobilayer exhibited a continuously tunable band gap under the biaxial strain. The heterostructure had a high absorption coefficient of up to 10⁵ cm⁻¹ both in the visible and ultraviolet light spectra, indicating that it could absorb photons with wavelengths of 400 to 760 nm. Such pronounced electronic and optical properties render the ZnO/WSe₂ heterobilayers a promising photocatalyst for the water splitting reaction, not only in ultraviolet light but also in the visible light spectrum.

Conventional strain sensors rarely have both a high gauge factor and a large strain range simultaneously, so they can only be used in specific situations where only a high sensitivity or a large strain range is required. However, for detecting human motions that include both subtle and large motions, these strain sensors can't meet the diverse demands simultaneously. Here, we come up with laser patterned graphene strain sensors with self-adapted and tunable performance for the first time. A series of strain sensors with either an ultrahigh gauge factor or a preferable strain range can be fabricated simultaneously via one-step laser patterning, and are suitable for detecting all human motions. The strain sensors have a GF of up to 457 with a strain range of 35%, or have a strain range of up to 100% with a GF of 268. Most importantly, the performance of the strain sensors can be easily tuned by adjusting the patterns of the graphene, so that the sensors can meet diverse demands in both subtle and large motion situations. The graphene strain sensors show significant potential in applications such as wearable electronics, health monitoring and intelligent robots. Furthermore, the facile, fast and low-cost fabrication method will make them possible and practical to be used for commercial applications in the future.

An ultrasensitive strain sensor with a wide strain range based on graphene armour scales is demonstrated in this paper. The sensor shows an ultra-high gauge factor (GF, up to 1054) and a wide strain range (ε = 26%), both of which present an advantage compared to most other flexible sensors. Moreover, the sensor is developed by a simple fabrication process. Due to the excellent performance, this strain sensor can meet the demands of subtle, large and complex human motion monitoring, which indicates its tremendous application potential in health monitoring, mechanical control, real-time motion monitoring and so on.