As unique building blocks for next‐generation optoelectronics, high‐quality 2D p–n junctions based on semiconducting transition metal dichalcogenides (TMDs) have attracted wide interest, which are urgent to be exploited. Herein, a novel and facile electron doping of WSe2 by cetyltrimethyl ammonium bromide (CTAB) is achieved for the first time to form a high‐quality intramolecular p–n junction with superior optoelectronic properties. Efficient manipulation of charge carrier type and density in TMDs via electron transfer between Br− in CTAB and TMDs is proposed theoretically by density functional theory (DFT) calculations. Compared with the intrinsic WSe2 photodetector, the switching light ratio (Ilight/Idark) of the p–n junction device can be enhanced by 103, and the temporal response is also dramatically improved. The device possesses a responsivity of 30 A W−1, with a specific detectivity of over 1011 Jones. In addition, the mechanism of charge transfer in CTAB‐doped 2D WSe2 and WS2 are investigated by designing high‐performance field effect transistors. Besides the scientific insight into the effective manipulation of 2D materials by chemical doping, this work presents a promising applicable approach toward next‐generation photoelectronic devices with high efficiency.

Monolayer hexagonal MoS2 flakes with abundant sulphur vacancies directly grown by CVD have remarkably improved catalytic efficiency compared with the triangular ones, superior to existing MoS2 grown by CVD for electrochemical hydrogen production.

2D materials with tailored morphologies exhibit distinctive shape-dependent properties especially in electrocatalysis and gas sensing, extending their applications in nanoelectronics. Atomic-layer tungsten disulfide (WS 2 ) stands out as a promising candidate, but the controllable synthesis of WS 2 still faces unavoidable obstacles, such as strict parameter requirements, low efficiency and serious pollution during the preparation. Here we report an elegant technique for growing homogeneousluminescence WS 2 monolayer with desired shapes and developed electrochemical properties, through the improved chemical vapor deposition method with a semi-closed airflow environment. It is an effective, economic and especially environment-friendly approach with atmospheric pressure and hydrogen-free condition, aiming at synthesizing high-quality and large-scale monolayer WS 2 crystals with only one heating zone. Compared with the existing methods, this one significantly minimizes the sulphur contamination to the environment and equipment, enabling the reuse of quartz tube and reducing the cost. More importantly, different shapes of WS 2 domains with high crystalline and excellent homogeneity of luminescent intensity are controllable by adjusting the growth temperatures. In addition to the good electrical transport performance of WS 2 monolayer, the WS 2 domains with different morphologies exhibit modulated properties for catalyzing the electrochemical hydrogen evolution. This systematic study on shape-controlled growth and shape-dependent electrochemical performances of WS 2 will further push forward their practical applications.

Graphitic carbon nitride (g-C3N4) has been widely studied as a photocatalyst for the splitting of water to produce hydrogen. In order to solve the problems of limited number of active sites and serious recombination rate of charge-carriers, noble metals are needed as cocatalysts. Here, we selectively anchored Pt nanoparticles (NPs) to specific nitrogen species on the surface of g-C3N4 via heat treatment in argon–hydrogen gas mixture, thus achieving g-C3N4 photocatalyst anchored by highly dispersed homogeneous Pt NPs with the co-existed metallic Pt0 and Pt2+ species. The synergistic effect of highly dispersed metallic Pt0 and Pt2+ species makes the catalyst exhibit excellent photocatalytic performance. Under the full-spectrum solar light irradiation, the photocatalytic hydrogen production rate of the photocatalyst is up to 18.67 mmol·g−1·h−1, which is 5.1 times of the catalyst prepared by non-selective deposition of Pt NPs.