Green innovation, i.e., innovation consisting of new or improved products, processes, services, and management, can both add value to a firm and significantly reduce the negative impact on the environment [9]. Compared to traditional innovation, which has economic performance as its main objective, it can be found that green innovation places more emphasis on the adoption of new technologies and ideas to achieve efficient use of resources and effective reduction in pollution, and to obtain the corresponding economic performance under these premises. There are many factors that influence green innovation in a country, among which the acquisition of new products, technologies, and models from abroad through OFDI is an important way to improve the level of green innovation in the country. At present, there are basically three types of studies on the relationship between OFDI and green innovation. The first is the “promotion theory”, because some scholars believe that OFDI can promote the improvement of China’s green innovation level, and its mechanism of action mainly works through two channels: the technology spillover effect [10] and the industrial structure optimization effect [11]; the second is “inhibition theory”, because some scholars argue that OFDI does not positively promote the level of green innovation in China, and its data test finds that OFDI has a crowding-out effect on domestic investment [12,13], and the characteristic portion of OFDI used for technology seeking is relatively small. The third is the “non-linear theory”, which comes from the view of some scholars that the impact of OFDI on green innovation may be “non-linear”. It is believed that innovation itself is a complex system that covers different innovation segments and cannot be measured by a single indicator that cuts across all segments. In addition, some scholars explored green innovation in stages based on innovation value chain theory, and found that OFDI has heterogeneous effects on green innovation in different innovation stages [7,14].

Binary innovation refers to the division of innovation activities into exploratory innovation and exploitative innovation [15], where the former refers to the development and integration of new knowledge and technology to meet new customers or emerging market needs based on the development of new products and services, while the latter refers to the optimization of existing products or services by firms through mining, refining, integrating, and improving existing knowledge and technology to meet existing [16]. A comparison of the two reveals that exploratory innovation is a large-scale, more radical innovation behavior, while exploitative innovation is a small-scale, incremental innovation behavior [15]. Even so, the two are not mutually exclusive or incompatible, and it is necessary to emphasize the balanced development of exploratory and exploitative innovation in the innovation process. The impact of OFDI on binary innovation has been studied by scholars from different perspectives. According to some scholars, there are essential differences between the home and host country binary networks in which OFDI is located. Under different network characteristics, if the home country has stronger business network relations, then the development of exploitative innovation will be more favorable [17]. However, a stable business posture for a long time may also cause firms to form inertia and hinder exploratory innovation [18]; business network relationships in the host country, on the contrary, can lead to the complexity of inter-firm relationships by providing more heterogeneous resources as well. While this favors firms undertaking exploratory innovation, it discourages exploitative innovation [19], where the impact of OFDI on binary innovation is mainly realized through the competition effect, the human capital flow effect, and the model imitation effect. Additionally, some scholars examined the dynamic evolutionary domain of OFDI affecting binary innovation. The firm life cycle has different effects when it is at different stages, specifically, the firm size, profitability, and resource redundancy are reflected in the growth, maturity, and decline stages of the firm. Therefore, OFDI has different effects on the promotion of binary innovation and binary interaction [20]; moreover, the passage of time highlights the phenomenon that OFDI has a sustainable effect on exploratory innovation represented by invention patents, while it has a smaller and less sustainable effect on exploitative innovation represented by utility models and design patents [21].