Does international collaborative R&D expand the boundaries of regional low-carbon innovation?

Amid intense market competition, this study examines how international collaborative R&D influences the boundaries of regional low-carbon innovation. Using the “Behavior-Capability-Outcome” analytical framework and provincial panel data for China’s manufacturing industry from 2012 to 2023, it further investigates the roles of regional absorptive capacity, digital industrial geographic agglomeration, and digital industrial virtual agglomeration. The results show that international collaborative R&D has an inverted U-shaped relationship with regional low-carbon innovation boundaries. Regional absorptive capacity partially mediates this relationship, while digital industrial geographic agglomeration and digital industrial virtual agglomeration flatten the inverted U-shaped curve. The effects also vary across geographic divisions and levels of environmental regulation. These findings clarify the nonlinear relationship and underlying mechanisms between international collaborative R&D and regional low-carbon innovation boundaries, providing targeted policy insights for expanding such boundaries across regions.