Herein, the authors explicitly reveal the dual‐functions of N dopants in molybdenum disulfide (MoS2) catalyst through a combined experimental and first‐principles approach. The authors achieve an economical, ecofriendly, and most efficient MoS2‐based hydrogen evolution reaction (HER) catalyst of N‐doped MoS2 nanosheets, exhibiting an onset overpotential of 35 mV, an overpotential of 121 mV at 100 mA cm−2 and a Tafel slope of 41 mV dec−1. The dual‐functions of N dopants are (1) activating the HER catalytic activity of MoS2 S‐edge and (2) enhancing the conductivity of MoS2 basal plane to promote rapid charge transfer. Comprehensive electrochemical measurements prove that both the amount of active HER sites and the conductivity of N‐doped MoS2 increase as a result of doping N. Systematic first‐principles calculations identify the active HER sites in N‐doped MoS2 edges and also illustrate the conducting charges spreading over N‐doped basal plane induced by strong Mo 3d–S 2p–N 2p hybridizations at Fermi level. The experimental and theoretical research on the efficient HER catalysis of N‐doped MoS2 nanosheets possesses great potential for future sustainable hydrogen production via water electrolysis and will stimulate further development on nonmetal‐doped MoS2 systems to bring about novel high‐performance HER catalysts.

When a high-power laser beam is focused into liquid, it results in a shock wave emission and cavitation bubble generation. Upon inserting a rigid substrate into the liquid, the bubbles migrate towards the substrate due to the Bjerknes attractive force. Due to bubble–substrate and/or bubble–free-surface interaction, a high-speed liquid jet is formed during bubble collapse, and a collapse shock wave is generated at the moment of bubble collapse near the substrate. These shock waves and liquid jet induce large forces acting on the substrate to remove particles from it. For a substrate several millimeters away from the laser focus point, the collapse shock wave and liquid jet play key roles in removal of particles. The cleaning efficiency increases with an increase of laser fluence and decreases with an increase of distance between substrate surface and laser beam focus point or depth below liquid surface. In a case of bubbles close to substrate and liquid-surface boundaries, implosion of the bubbles will give rise to shock waves and liquid jets oblique to the substrate surface with the parallel and perpendicular components of the forces onto the particles. These oblique liquid jets and shock waves result in high cleaning efficiency. A liquid, such as alcohol and commercial washing solution, as the surrounding medium, rather than air or vacuum, can reduce adhesion force and enhance cleaning efficiency.

Strain engineering is an effective way to modify functional properties of thin films. Recently, the importance of octahedral rotations in pervoskite films has been recognized in discovering and designing new functional phases. Octahedral behavior of SrRuO3 film as a popular electrode in heterostructured devices is of particular interest for its probable interfacial coupling of octahedra with the functional overlayers. Here we report the strain engineering of octahedral rotations and physical properties that has been achieved in SrRuO3 films in response to the substrate-induced misfit strains of almost the same amplitude but of opposite signs. It shows that the compressively strained film on NdGaO3 substrate displays a rotation pattern of a tetragonal phase whilst the tensilely strained film on KTaO3 substrate has the rotation pattern of the bulk orthorhombic SrRuO3 phase. In addition, the compressively strained film displays a perpendicular magnetic anisotropy while the tensilely strained film has the magnetic easy axis lying in the film plane. The results show the prospect of strain engineered octahedral architecture in producing desired property and novel functionality in the class of perovskite material.