## 3 Conclusions and Perspectives  
AEMWE is a technology with tremendous potential for development, being the major challenge to overcome their high alkaline degradation. The main conclusions and perspectives are summarized below for each of the hot topics addressed.  
Membranes:  
Commercial membranes are available, differing in chemistry and thickness, that may contribute to system improvement and accelerate the research pathway. In particular, Sustainon membranes constitute a promising option due to their good performance and durability. Different combinations using diverse anion exchange cationic groups linked to different polymer backbones must be investigated to develop more conductive, stable, and durable membranes. Moreover, all the AEMWE components should be optimized together, and experimental characterization recurring to IV curves, EIS, CV, and in situ/ex situ catalysts' characterization should be performed for a deeper understanding of components' interactions and the contribution of each component for performance losses and durability.  
Catalysts:  
Transition metal catalysts are already used with good results in OER, although few studies have been conducted reporting their use for HER. An interesting option leading to a simpler MEA construction is the use of bifunctional electrodes presenting good performances, considering both OER and HER reactions. Consequently, it is essential to further investigate the reaction mechanisms to a deep knowledge of the internal properties of these catalyst materials facilitating the development of more efficient catalysts (with lower overpotentials). Regarding the catalysts, deposition in the membrane (CCM approach) is preferable to guarantee better adhesion and to permit the use of lower catalyst loadings. Nevertheless, further optimization is essential considering ink composition and guaranteeing an appropriate electrode-membrane contact during assemblage.  
Durability:  
The biggest concern when developing new materials, catalysts, and membranes, besides their performance, is undoubtedly their durability. Some materials appear to be promising options, but once tested under real operating conditions, they demonstrated poor durability. ASTs protocols, mimetizing the dynamic RES operating conditions, must be widely implemented, allowing a quick durability assessment of the materials.  
Feeding solutions:  
The most used feeding solution is a hydroxide solution due to an improvement in AEMWE conductivity and, consequently, in performance. However, considering the shortage of fresh water, the desired options are seawater or treated wastewater. These options remain an ambitious scenario since AEMWE components quickly deteriorate with contaminants presented in impure waters, and/or the performance is lower due to competitive reactions occurring in the electrodes. More efforts in developing more robust and less susceptible to feed-water impurities AEMWE systems are mandatory to improve their lifetimes and reduce the overall cost.  
**Funding:** This work is financially supported by national funds through the FCT/MCTES (PIDDAC), under the project PTDC/EQU-EQU/1707/2020. This work was also financially supported by LA/P/0045/2020 (ALiCE), UIDB/00532/2020 and UIDP/00532/2020 (CEFT), funded by national funds through FCT/MCTES (PIDDAC).  
**Conflicts of Interest:** The author declares no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.