Three-dimensional ordering of two-dimensional nanomaterials has long been a challenge. Simultaneously, diamond nanomaterials are difficult to synthesize due to the harsh synthesizing conditions required. Here, we report substrate-crystal-orientation dependent growth of diamond nanosheets (DNSs) by chemical vapor deposition, which generates different DNS arrays on different substrates. The DNSs are grown by the in-plane epitaxy of the diamond {111} planes. So the arrays are highly ordered and solely determined by the spatial orientation of the {111} planes in the diamond FCC structure. The DNSs grown on the {110}, {111}, {001}, and {113} oriented substrates show inclination angles ranging from 90 to 29.5°. The DNSs with larger inclination angles grow preferentially, forming parallelogram arrays with inclination angles of 90° on the {110} substrates and parallel-line arrays with inclination angles of 80° on the {113} substrates. The density, thickness, size, and morphology of the DNSs have been well controlled. The present understanding and materials are highly promising for many applications such as sensors, catalysis, photonics, thermal management, and electronics.

Diamond/graphite hybrid nanosheets (DGNSs) have been epitaxially grown on boron-doped diamond (BDD) films from CH/H mixture gas by microwave plasma chemical vapor deposition. The DGNSs are vertically aligned on the crystal facets of the BDD films uniformly, densely, and orderly. The DGNSs are composed of the core diamond sheets and the surface graphitic overlayers, which possess an open edge structure. By posttreatment in NH atmosphere in a microwave plasma or a tube furnace, the N-doped DGNSs (NDGNSs) were obtained. The electrocatalytic performance toward oxygen reduction reaction (ORR) for the DGNSs was greatly enhanced after doping with N, and the doped pyridinic N contributes more to the ORR. The electrocatalytic activity for ORR of the NDGNSs doped at 650 °C in NH in a tube furnace is the highest in all of the samples, which is comparable to the commercial Pt/C. The present work provides a novel electrocatalyst for the ORR with high performance.