Herein, we demonstrate an ammonia nitridation approach to synthesize self-supported ordered mesoporous metal nitrides (CoN and CrN) from mesostructured metal oxide replicas (Co3O4 and Cr2O3), which were nanocastly prepared by using mesoporous silica SBA-15 as a hard template. Two synthetic routes are adopted. One route is the direct nitridation of mesoporous metal oxide nanowire replicas templated from SBA-15 to metal nitrides. By this method, highly ordered mesoporous cobalt nitrides (CoN) can be obtained by the transformation of Co3O4 nanowire replica under ammonia atmosphere from 275 to 350 °C, without a distinct lose of the mesostructural regularity. Treating the samples above 375 °C leads to the formation of metallic cobalt and the collapse of the mesostructure due to large volume shrinkage. The other route is to transform mesostructured metal oxides/silica composites to nitrides/silica composites at 750–1000 °C under ammonia. Ordered mesoporous CrN nanowire arrays can be obtained after the silica template removal by NaOH erosion. A slowly temperature-program-decrease process can reduce the influence of silica nitridation and improve the purity of final CrN product. Small-angle XRD patterns and TEM images showed the 2-D ordered hexagonal structure of the obtained mesoporous CoN and CrN nanowires. Wide-angle XRD patterns, HRTEM images, and SAED patterns revealed the formation of crystallized metal nitrides. Nitrogen sorption analyses showed that the obtained materials possessed high surface areas (70–90 m2 g−1) and large pore volumes (about 0.2 cm3 g−1).
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