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 ${\text{mmol}}_{{\text{H}}_2}\cdot {{\text{g}}_{\text{cat}}}^{-1}\cdot {\text{h}}^{-1}$) 5.5× higher than Cu_xSb_yS nanotubes (126.21 ${\text{mmol}}_{{\text{H}}_2}\cdot {{\text{g}}_{\text{cat}}}^{-1}\cdot {\text{h}}^{-1}$) and 198.9× that of Cu nanoparticles (3.47 ${\text{mmol}}_{{\text{H}}_2}\cdot {{\text{g}}_{\text{cat}}}^{-1}\cdot {\text{h}}^{-1}$), 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.