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Submicrometer-sized capsules made of Si nanoparticles wrapped by crumpled graphene shells were made by a rapid, one-step capillary-driven assembly route in aerosol droplets. Aqueous dispersion of micrometer-sized graphene oxide (GO) sheets and Si nanoparticles were nebulized to form aerosol droplets, which were passed through a preheated tube furnace. Evaporation-induced capillary force wrapped graphene (a.k.a., reduced GO) sheets around the Si particles, and heavily crumpled the shell. The folds and wrinkles in the crumpled graphene coating can accommodate the volume expansion of Si upon lithiation without fracture, and thus help to protect Si nanoparticles from excessive deposition of the insulating solid electrolyte interphase. Compared to the native Si particles, the composite capsules have greatly improved performance as Li ion battery anodes in terms of capacity, cycling stability, and Coulombic efficiency.

Graphene oxide (GO) nanocolloids-sheets with lateral dimension smaller than 100 nm-were synthesized by chemical exfoliation of graphite nanofibers, in which the graphene planes are coin-stacked along the length of the nanofibers. Since the upper size limit is predetermined by the diameter of the nanofiber precursor, the size distribution of the GO nanosheets is much more uniform than that of common GO synthesized from graphite powders. The size can be further tuned by the oxidation time. Compared to the micrometer-sized, regular GO sheets, nano GO has very similar spectroscopic characteristics and chemical properties but very different solution properties, such as surface activity and colloidal stability. Due to higher charge density originating from their higher edge-to-area ratios, aqueous GO nanocolloids are significantly more stable. Dispersions of GO nanocolloids can sustain high-speed centrifugation and remain stable even after chemical reduction, which would result in aggregates for regular GO. Therefore, nano GO can act as a better dispersing agent for insoluble materials (e.g., carbon nanotubes) in water, creating a more stable colloidal dispersion.

Development of low‐cost, high‐performance, and bifunctional electrocatalysts for water splitting is essential for renewable and clean energy technologies. Although binary phosphides are inexpensive, their performance is not as good as noble metals. Adding a third metal element to binary phosphides (Ni‐P, Co‐P) provides the opportunity to tune their crystalline and electronic structures and thus their electrocatalytic properties. Here, ternary phosphide (NiCoP) films with different nickel to cobalt ratios via an electrodeposition technique are synthesized. The films have a triple‐layered and hierarchical morphology, consisting of nanosheets in the bottom layer, ≈90–120 nm nanospheres in the middle layer, and larger spherical particles on the top layer. The ternary phosphides exhibit versatile activities that are strongly dependent on the Ni/Co ratios and Ni0.51Co0.49P film is found to have the best electrocatalytic activities for both hydrogen evolution reactions and oxygen evolution reactions. The high performance of the ternary phosphide film is attributed to enhanced electric conductivity so that reaction kinetics is accelerated, enlarged surface area due to the hierarchical and three‐layered morphology, and increased local electric dipole so that the energy barrier for the water splitting reaction is lowered.

The electronic metal–support interaction (EMSI) plays a crucial role in catalysis as it can induce electron transfer between metal and support, modulate the electronic state of the supported metal, and optimize the reduction of intermediate species. In this work, the tailoring of electronic structure of Pt single atoms supported on N‐doped mesoporous hollow carbon spheres (Pt1/NMHCS) via strong EMSI engineering is reported. The Pt1/NMHCS composite is much more active and stable than the nanoparticle (PtNP) counterpart and commercial 20 wt% Pt/C for catalyzing the electrocatalytic hydrogen evolution reaction (HER), exhibiting a low overpotential of 40 mV at a current density of 10 mA cm−2, a high mass activity of 2.07 A mg−1Pt at 50 mV overpotential, a large turnover frequency of 20.18 s−1 at 300 mV overpotential, and outstanding durability in acidic electrolyte. Detailed spectroscopic characterizations and theoretical simulations reveal that the strong EMSI effect in a unique N1−Pt1−C2 coordination structure significantly tailors the electronic structure of Pt 5d states, resulting in promoted reduction of adsorbed proton, facilitated H−H coupling, and thus Pt‐like HER activity. This work provides a constructive route for precisely designing single‐Pt‐atom‐based robust electrocatalysts with high HER activity and durability.