Unique Zinc Germanium Oxynitride Hyperbranched Nanostructures with Enhanced Visible‐Light Photocatalytic Activity for CO 2 Reduction

Unique (Zn 1+ x Ge)(N 2 O x ) hyperbranched nanostructures with rough surfaces were prepared by nitriding Zn 2 GeO 4 bundles at 700 °C. In this process, the constituent smooth nanobelts of the Zn 2 GeO 4 bundles are transformed into chains composed of nanoparticles; therefore, the (Zn 1+ x Ge)(N 2 O x ) hyperbranched nanostructures have a lager specific surface area, which is twice that of the Zn 2 GeO 4 precursor. Compared to reference (Zn 1+ x Ge)(N 2 O x ) particles synthesized by a solid‐state reaction approach as well as (Zn 1+ x Ge)(N 2 O x ) prepared by nitriding Zn 2 GeO 4 nanorods at 700 °C for 6 h, the optimal hyperbranched (Zn 1+ x Ge)(N 2 O x ) particles exhibit enhanced activity for the photoreduction of CO 2 to CH 4 under visible light due to their unique 3D hyperbranched nanostructure. A GaN–ZnO solid solution with a 3D microsphere structure can be obtained by a similar process. This work provides valuable information for the preparation of oxynitrides with high specific surface areas.