## 2 Research Background
### Related Work  
The related work in this research was explored in order to spot the research gap in the existing literature (see Table 1). Similar to this review study, [PERSON] et al. [24] carried out an extensive literature review of 192 papers to synthesize knowledge about actors and institutions of mobile payment technologies. Similarly, [PERSON] et al. [25] conducted a review on the key technological factors related to mobile payments. Their study identified 17 key technological factors for using mobile payment technologies. Another review study by [PERSON] et al. [18] focused on the past, present and future of mobile payment technology. They focused on the impacts of the social and cultural aspects of mobile payment methods. The study also included comparisons between mobile and traditional payment services. [PERSON] and [PERSON] [15] reviewed a growing volume of studies on mobile e-wallet adoption in developing countries. The study found that electronic wallets have emerged as one of the most popular digital payment methods and gained more attention from researchers. [PERSON] et al. [19] reviewed 51 papers on e-payment adoption and highlighted the use of scope, methodology and information system models.  
[PERSON] et al. [17] conducted a review of 54 papers concerning blockchain-enabled applications. The study included a systematic classification of applications related to blockchain technology and established trends and key areas of research. Their study highlighted the potential disruption of blockchain technology to revolutionize 'business-as-usual' practices. Another study by [PERSON] et al. [26] explored 21 articles to determine factors  
\begin{table}
\begin{tabular}{c c c} \hline
**Review by** & **No. of Papers** & **Focus of the Study** \\ \hline Our review (2021) & 58 &
\begin{tabular}{c} Emerging technologies of digital payment and \\ challenges associated with them \\ \end{tabular} \\ \hline [PERSON] and [PERSON] [15] & 77 & Mobile e-wallet in emerging economies \\ \hline [PERSON], [PERSON] and [PERSON] [19] & 51 & Adoption of e-payment systems \\ \hline [PERSON], [PERSON] and [PERSON] [17] & 54 & Applications related to blockchain technology \\ \hline [PERSON], [PERSON] and [PERSON] [24] & 192 & Mobile money and payment \\ \hline [PERSON] et al. [18] & 73 & Past, present and future of mobile payment technology \\ \hline [PERSON], [PERSON] and [PERSON] [26] & 21 & Adoption of digital payment technologies \\ \hline [PERSON], [PERSON] and [PERSON] [25] & 54 & Technological factors of mobile payment \\ \hline \end{tabular}
\end{table}
Table 1: Previous reviews vs. this review.  
influencing the adoption of digital payments, showing the drivers and inhibitors for the adoption of the digital payment technologies.  
As mentioned above, the previously published literature reviews were mostly focused on the adoption of digital payment technologies, such as the adoption of e-payment systems and mobile e-wallet payment methods' adoption in developing countries. The previous reviews also focused on a particular technology used for digital payments, such as blockchain-based applications, mobile money, e-wallet and mobile payments. In contrast, this paper provides a systematic summary of the widely dispersed knowledge on emerging technologies used in digital payment systems. Digital payments occur through a variety of technologies, such as debit cards, credit cards, ATMs, online transactions and mobile phones. Through a systematic literature review (SLR) of empirical studies on digital payments, the paper aims to map out the existing knowledge on emerging digital payment technologies and the challenges associated with them.