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Flower-like In2O3/ZnO heterostructures consisting of the assembled needle-like nanorods derived from In2O3 precursor/ZIF-8 have been prepared by a two-step approach. Flower-like In2O3/ZnO structures can be achieved by adjusting the nucleation competition and crystal surface matching of In2O3 and ZnO, leading to the enhancement of gas adsorption on the surface, chemical reaction kinetics, and the electron transport efficiency. In/Zn-2 sensors exhibit excellent gas-sensing response value of 188.01 to 100 ppm triethylamine at 120 °C as well as good gas selectivity, long-term stability, and linear relationship compared with pure In2O3, mainly attributed to the accelerated multi-orientation electron transport mechanism within flower-like In2O3/ZnO heterostructures. In addition, In/Zn-2 samples can be utilized to detect the practical triethylamine gas released during the storage of marine organism (fishes).

C-N/Co/Ti composites derived from ZIF-67@TiO2 precursors have been fabricated by a facile thermal treatment process. The morphology and composition are highly dependent on the available parameters inferring of exact hydrolysis of tetrabutyl titanate and sintering temperature. The obtained hierarchical microstructure is composed of numerous dodecahedron-like hollow boxes decorated with in-situ growth of size-tunable and twisting nanotubes on surfaces. The effective elemental separation of Ti and Co on the upper and lower ends of nanotubes can be realized by regulating the ionic migration and crystalline phase formation process at a high temperature. The as-prepared C-N/Co/Ti composites exhibit the enhanced electrocatalytic activities to oxygen reduction reaction (ORR) via a favorable four-electron pathway and the desired reaction kinetics with the low Tafel slope (67.8 mV dec−1), as well as the excellent methanol tolerance in comparison with the Pt/C electrocatalysts. The superior ORR electrocatalytic performance would be mainly contributed to the combination of the designed multi-phase composition, the enhanced surface adsorption/desorption, the modified surface/interface electron transfer mechanism, and the constructed Co/Ti double-active sites on different locations of microstructure. The present work presents a new insight for the synthesis of C-N-based inorganic composite with outstanding electrocatalytic behavior for ORR process.