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Developing efficient, nonprecious, and durable electrocatalysts with favorable nanostructures is a persistent challenge yet is significant for the hydrogen evolution reaction (HER). Herein, for the first time, a rationally designed strategy is reported for the synthesis of hierarchical hollow MoP nanospheres anchored on N,P,S co‐doped porous carbon (hs‐MoP/NPSC). Importantly, the porous shell of the hollow nanosphere is constructed of a number of interwoven MoP subunits, which is beneficial for exposing surface active sites as much as possible and promoting the mass transport during the HER process. In addition, the heteroatom‐enriched porous carbon networks can further reduce the electron/ion transfer resistance. As expected, the hs‐MoP/NPSC electrocatalyst exhibits an encouraging HER activity with a low overpotential of only 70 mV at a current density of 10 mA cm−2, a small Tafel slope, and long‐term durability in alkaline media, outperforming most of reported Pt‐free MoP‐based electrocatalysts to date. This present work not only develops a highly efficient electrocatalyst for HER but also opens up opportunities to engineer novel architectures for various applications.

Thermally conductive yet electrically insulating two-dimensional boron nitride nanosheets (BNNSs) have been an ideal choice for the enhanced fillers for improving thermal properties of polymer-based composites. As a nanofiller with an ultrahigh aspect ratio, BNNSs result in conspicuous stacking along the planar direction in the preparation of composites, which results in strong anisotropy of heat transfer and suppresses out-plane thermal dissipation. Thus, it is necessary to facilitate the out-plane heat transfer by building a favorable microstructure. Focusing on the structural design of the nanofiller itself here, we have fabricated a novel three-dimensional nanofiller with improved out-plane connections. Carbon nanotubes (CNTs) have been grown in situ on the surface of BNNSs using chemical vapor deposition. Utilizing these sandwich-like nanostructure BNNSs/CNTs as fillers in the composites, we have assembled diverse sorts of composites, such as flexible films, scleroid 3D mats, painted ink, and viscous grease. Simultaneously, their thermal and insulating properties have been evaluated. A nearly 330% enhancement of out-plane thermal conductivity from the control sample filled with pristine BNNS is achieved, and the composite also exhibits good electrical resistivity of above 7.5 × 1010 Ω mm. The results indicate that the BNNS/CNT filler has superior thermal performance over the original BNNS while maintaining a satisfactory electrical resistivity to avoid short-circuits in high-power electronics. Furthermore, the prepared grease used as a thermal interface material shows impressive heat dissipation performance when applied on a running computer.