Zinc oxide (ZnO) nanorods are grown hierarchically on cuprous oxide (Cu₂O) nanoneedles to form a Cu₂O/ZnO hetero-nanobrush assembly. This increases the overall aspect ratio, which helps to enhance the field emission properties of the system. Also, the charge separation and transport are facilitated because of the multiple p–n junctions formed at p-Cu₂O/n-ZnO interfaces and quasi-1-D structures of both the materials, respectively. This helps to significantly enhance the photocatalytic properties. As compared to only Cu₂O nanoneedles, the Cu₂O/ZnO hetero-nanobrush shows excellent improvement in both field emission and photocatalytic applications.

Cu₂O nanoneedles are synthesized on a copper substrate by a simple anodization and reducing ambient annealing protocol. ZnO nanorods are grown on ITO coated glass by a low temperature chemical route. The electronic and photo-response properties of the p-Cu₂O/n-ZnO flip-chip heterojunction are then studied and analyzed. We show that the I–V characteristic is rectifying and the junction exhibits a good photoresponse (∼120% under 1 V reverse bias) under AM 1.5 (1 Sun) illumination. This nano-heterojunction photo-response is far stronger as compared to that of a pulsed laser deposited thin film p-Cu₂O/n-ZnO heterojunction, which can be attributed to higher junction area in the former case.

Metal hydrides such as MgH₂ and NaBH₄ are among the materials for with the highest potential solid-state hydrogen storage. However, unlike gas and liquid storage, a dehydrogenation process has to be done prior to hydrogen utilization. In this context, the hydrolysis method is one of the possible methods to extract or generate hydrogen from the materials. However, problems like the MgH₂ passivation layer, high cost and sluggish self-hydrolysis of NaBH₄ are the known limiting factors for this process, but they can be overcome with the help of catalysts. In this works, selected studies have been reviewed on the performance of catalysts like chloride, oxide, fluoride, platinum, ruthenium, cobalt and nickel-based on the MgH₂ and NaBH₄ system. These studies show a significant enhancement in the amount of hydrogen released as compared to the hydrolysis of the pure MgH₂ and NaBH₄. Therefore, the addition of catalysts is proven as one of the options in improving hydrogen generation via the hydrolysis of MgH₂ and NaBH₄.