MXenes with versatile chemistry and superior electrical conductivity are prevalent candidate materials for energy storage and catalysts. Inspired by recent experiments of hybridizing MXenes with carbon materials, here we theoretically design a series of heterostructures of N-doped graphene supported by MXene monolayers as bifunctional electrocatalysts for the oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Our first-principles calculations show that the graphitic sheet on V2C and Mo2C MXenes are highly active with an ORR overpotential down to 0.36 V and reaction free energies for the HER approaching zero, both with low kinetic barriers. Such outstanding catalytic activities originate from the electronic coupling between the graphitic sheet and the MXene, and can be correlated with the pz band center of surface carbon atoms and the work function of the heterostructures. Our findings screen a novel form of highly active electrocatalysts by taking advantage of the fast charge transfer kinetics and strong interfacial coupling of MXenes, and illuminate a universal mechanism for modulating the catalytic properties of two-dimensional hybrid materials.

MBenes hold many merits for electrocatalysis of the nitrogen reduction reaction, including outstanding stability in aqueous environments, excellent electrical conductivity, an inhibited hydrogen evolution reaction, and highly active boron and metal surfaces.

Boron nitride (BN), with outstanding stability and robustness in diverse polymorphs, possesses many advantageous properties for industrial applications. Activation of BN materials for nonmetal catalysts is among the most revolutionary and challenging tasks. Taking advantage of quantum size effect and synergistic effect, here we exploit boron nitride nanotubes (BNNTs) encapsulating early transition metal nanowires, which is experimentally feasible, for nitrogen fixation and ammonia synthesis. Using firstprinciples calculations and microkinetic modeling, we show that the coexisting occupied and unoccupied p states of B atoms in filled BNNTs can effectively mimic the d states of transition metal. They act as electron reservoirs with tunable orbital energies and occupancy, which are beneficial for associative N 2 adsorption and hydrogenation. Due to the competition between thermodynamics of gas adsorption and kinetics of hydrogenation reaction, the activity can be optimized by controlling the type of metal filler and size of BN nanotube, achieving a turnover frequency competitive to that of benchmark Fe catalyst. These results manifest a universal strategy for activating BN nanomaterials as a promising family of robust and efficient catalysts and provide vital insights into the activity− band structure relationship for p-block nonmetal catalysts.

The enhanced green fluorescence protein (EGFP) is efficiently encapsulated in silica nanoparticle by multiple covalent bonds. The silica encapsulation greatly increases EGFP's fluorescence intensity and stabilities against protease, denaturant and heat, making it a potential fluorescence probe for cellular imaging.

Activation of p-block elements to replace the rare and precious transition metals for renewable energy applications is highly desirable. In this review, we go over recent experimental and theoretical progress on the low-dimensional non-metal materials for clean energy production, including carbon, silicon, oxide, boron, and phosphorus-based nanostructures, with the p-block elements serving as active sites. We aim to elucidate the mechanism for triggering activity in different kinds of non-metal systems, and extract general principles for controlling the p-orbital-mediated reactivity from a theoretical point of view. The perspectives and challenges for developing high-efficiency non-metal catalysts are provided in the end.