Single-layer single-crystalline SnSe nanosheet with four-atomic thickness of ~1.0 nm and lateral size of ~300 nm is presented here by using a one-pot synthetic method. It is found that 1,10-phenanthroline plays an important role in determining the morphology of the SnSe product as three-dimensional SnSe nanoflowers are obtained in the absence of 1,10-phenanthroline while keeping other reaction parameters the same. The evolution process study discloses that single-crystalline nanosheets are obtained from the coalescence of the SnSe nucleus in an orientated attachment mechanism. Band gap determination and optoelectronic test based on hybrid films of SnSe and poly(3-hexylthiophene) indicate the great potential of the ultrathin SnSe nanosheets in photodector and photovoltaic, and so forth.

Electrochemical actuators directly converting electrical energy to mechanical energy are critically important for artificial intelligence. However, their energy transduction efficiency is always lower than 1.0% because electrode materials lack active units in microstructure, and their assembly systems can hardly express the intrinsic properties. Here, we report a molecular-scale active graphdiyne-based electrochemical actuator with a high electro-mechanical transduction efficiency of up to 6.03%, exceeding that of the best-known piezoelectric ceramic, shape memory alloy and electroactive polymer reported before, and its energy density (11.5 kJ m−3) is comparable to that of mammalian skeletal muscle (~8 kJ m−3). Meanwhile, the actuator remains responsive at frequencies from 0.1 to 30 Hz with excellent cycling stability over 100,000 cycles. Furthermore, we verify the alkene–alkyne complex transition effect responsible for the high performance through in situ sum frequency generation spectroscopy. This discovery sheds light on our understanding of actuation mechanisms and will accelerate development of smart actuators.

A photoactuator based on a tubular-shaped graphene composite bimorph is fabricated and shows reversible photoactuation with fast response and large deformation (deformation angle of ca. 479° in only 3.6 s), which is mostly attributed to the interfacial thermal stress. Various photoactuator devices based on the tubular bimorph, including a smart box and crawler-type robot that can mimic tank-track motion, are designed.