tech-innovation(GT) related to improving the efficiency of fossil energy is stronger than that of clean technology(CT) related to the use of renewable energy. This suggests that for a large economy such as China, where coal is still the dominant source of energy consumption, the short-term local benefits of improving air quality and health through the use of grey tech-innovation to improve energy and industrial structure are still important to balance the cost of carbon mitigation.

This paper studies the impact of carbon trading policies on breakthrough low-carbon technological innovation through a difference-in-differences model based on the panel data of 30 provinces in China. Through descriptive statistics, regression analysis, a robustness test and heterogeneity analysis of the data, the results show that: (1) carbon trading policy has a significant effect on overall low-carbon technological innovation and gradual low-carbon technological innovation, and carbon trading policy lag can significantly promote breakthrough low-carbon technological innovation. (2) The timeliness of carbon trading policy in promoting breakthrough low-carbon technological innovation is different in different regions. The effect can quickly be displayed in some provinces, but there is a lag effect in other provinces. (3) Lags in carbon trading policy have promoted a significant increase in renewable energy technology patents and CCS-related technology patents, and contributed more to the increase in renewable energy technology patents.

The cross-regional diffusion of low-carbon technology knowledge is conducive to the development of low-carbon technology and increases the emission reduction contribution of the wider land. However, the flow of low-carbon technology knowledge faces many obstacles such as information, geography, and local protectionism. This paper focuses on whether and how information infrastructure construction can promote the flow of low-carbon technology knowledge under the digital wave. Through the low-carbon technology patents of category Y02 under the classification standard of Cooperative Patent Classification (CPC) and by matching them to the city level to measure the low-carbon technology knowledge flow, empirical research finds that: information infrastructure cannot only directly promote the low-carbon technology knowledge flow, but also indirectly promote the low-carbon technology diffusion by increasing foreign direct investment and human capital. The role of information infrastructure in promoting low-carbon technology knowledge is more obvious in the central and western regions and non-resource-based cities. Finally, in view of the current development situation of low-carbon technology knowledge flows in China, the paper puts forward policy recommendations to vigorously promote the construction of information infrastructure, to gradually increase the network density and the number of network nodes, release the digital economic dividend, and form a spatial pattern of coordinated development of regional knowledge flows.