Plasmonic nanotubes are promising for photocatalysis due to their hollow structure, strong light−matter coupling, enhanced scattering, short charge paths, and abundant active sites. However, their synthesis is challenging, with few reports. Uniform Cu_xSb_yS nanotubes and Cu_xSb_yS/Cu dual-plasmonic heteronanostructures were synthesized via direct colloidal hot-injection by controlling reaction parameters. In ammonia borane methanol dehydrogenation, the heterostructure achieves a hydrogen production rate (690.17 mmol H₂ g⁻¹ cat. h⁻¹) 5.5× higher than Cu_xSb_yS nanotubes (126.21 mmol H₂ g⁻¹ cat. h⁻¹) and 198.9× that of Cu nanoparticles (3.47 mmol H₂ g⁻¹ cat. h⁻¹), demonstrating stability over 10 cycles. Synergistic effects drive activity: hollow structure improves light harvesting and surface exposure; Cu_xSb_yS/Cu interface enables charge separation and transfer, reducing recombination; strong plasmonic absorption enhances photon utilization. Results confirm electron transfer from Cu_xSb_yS to Cu, stabilizing nanoparticles and improving durability. Density functional theory identifies CH₃OBH₂NH₃ desorption (not O−H cleavage) as the rate-determining step, offering new mechanistic insight. This method enables applications in solar hydrogen production, environmental purification, and energy-efficient conversion for sustainable energy and green chemistry.