Theoretical research on environmental problems and economic growth began in the 1960s. Owing to the sharp decrease in the stock of earth resources at that time, humanity’s living environment was severely damaged, which triggered two environmental revolutions. In the first environmental revolution, people debated the relationship between ambient quality and economic development. Economists led by Meadows published a report called ‘Limits to Growth’, which found that exponential increases in population growth, food supply, capital investment, environmental pollution, and resource depletion can stall economic growth and that technological progress can only ease the time to reach the limits. The second environmental revolution raised the issue of sustainable development and proposed many reports related to sustainable development, which prompted economists to study and discuss the circumstance for the coordinated development of the economy and environment. The two environmental revolutions encouraged economists to discuss and research the relationship between the economy and the environment on a theoretical level in general. Empirical research comes later than theoretical research. In the early 1990s, some scholars conducted an empirical study on the relationship between the economy and the environment and discovered that the relationship between many environment pollution indicators and income per person showed a reversed ‘U-shaped’ curve; that is, the ambient quality worsened first and then enhanced with economic development [11,12,13]. Panayotou (1993) found that this curve is similar to the Kuznets curve hypothesis proposed by Kuznets (1955); thus, the curve was termed the ‘environment Kuznets curve (EKC) hypothesis’ for the first time. The latter is also known as the EKC curve [14].

Finance was included in environmental-related research, which was also initially developed around the EKC hypothesis [15,16]. With the deepening research, its content gradually reduces the influence of the EKC hypothesis and pays extra attention to the relationship between finance and the environment. Currently, three main viewpoints exist on the correlation between finance and the environment. The first viewpoint is that financial development contributes to enhancing environmental quality. Some scholars believe that finance can enhance environmental quality by promoting technological progress [17], adjusting the industry structure, alleviating the shortage of environmental protection funds for enterprises, optimising the allocation of financial resources [18], improving the conversion rate of deposits and loans [19], and promoting green project investment and financing [20]. The second view is that financial development will aggravate environmental pollution. Some scholars believe that financial development increases energy consumption and pollution emissions by easing corporate financing constraints to expand production capacity [21,22] and easing consumer budget constraints to stimulate commodity consumption [23,24]. The third point of view is that financial growth has a reversed U-shaped non-linear relation with environmental pollution that first promotes and then inhibits it [25,26]. In recent years, with the emergence of inclusive finance, researchers have studied the relationship between finance and the environment from the viewpoint of financial resource equality and found that inclusive finance can affect environmental pollution emissions through economic growth and technological innovation mechanisms [27]. Meanwhile, the research results show that the emission-reduction effect of inclusive finance shows threshold characteristics [28]. As a new financial product formed by the combination of financial technology and inclusive finance, DIF has been around for a short time, and relatively few studies exist on DIF and pollution emissions. However, existing research generally believes that DIF can affect pollution emissions in direct and indirect ways. In terms of direct effects, DIF is an organic integration of advanced digital technology and inclusive finance. Its essence is to transform the traditional financial system with the help of new digital technologies. DIF has realised the innovation of traditional inclusive financial products and services, giving DIF wider coverage, lower service costs, higher service efficiency, and more accurate service targets. According to the transaction cost theory, the renewal of and improvement in transaction methods caused by technological progress have greatly improved transaction efficiency. At the same time, it effectively reduces search costs, negotiation costs, information transmission costs, supervision costs, and breach of contract costs in the transaction process. As a technological revolution in the financial field, DIF has provided many conveniences for enterprises and consumers in terms of reducing transaction costs and breaking through geographical distance restrictions and reducing various inefficient market transactions. Based on the above theoretical logic that DIF can reduce transaction costs, it can be found that DIF itself has green attributes and is environmentally friendly. Some scholars believe that DIF is a significant path to enhance financial inclusion, which has an optimistic effect on economic development and people’s lives [29,30]. DIF has improved green economic benefits by advocating the concept of low-carbon life, raising public consciousness of environmental protection, and building an environmental protection service platform [31]. At the same time, DIF uses digital techniques to effectively alleviate the problem of information asymmetry between the offer and need sides of financial institutions and enterprises, alleviate the misallocation of financial resources, and restrain environmental pollution emissions [32].

In terms of indirect effects, some scholars believe that DIF can reduce pollution emissions through industrial structure upgrades [33], innovation effects [34], and entrepreneurial effects [35]. Specifically, the industrial structure upgrading path of DIF includes three aspects [36]. On the one hand, DIF improves the scope and efficiency of financial services, effectively reduces the problem of financial exclusion, optimises the allocation of resources, and guides the flow of factors to high-productivity industries, thereby encouraging the upgrade of industry structure; on the other hand, DIF promotes the growth of the digital economy, development of logistics, transportation, and other service industries through online consumption and industrial transformation and upgrading. Simultaneously, DIF promotes the upgrade of the consuming structure by easing the consumption budget constraints of low- and middle-income groups, thereby encouraging the upgrade of industry structure. Compared with the secondary industry, the service industries have the peculiarities of low investment and low pollution. Thus, industrial transformation and upgrading can help reduce pollution emissions. Some scholars believe that the innovation effect, the emission reduction path, of DIF occurs by alleviating the external financing constraints of technological innovation enterprises [37] and reducing the financial resource misallocation problem caused by financial exclusion and information asymmetry of startups [38] to promote technological innovation of enterprises and reduce pollution emissions.