**7. Conclusion and future perspective**

Based on the reported research trends, new emerging materials such as HEAs and metal hydrides show the potential and future technology in energy conversion and storage respectively. The second generation of HEAs illustrate the higher electrocatalytic efficiency and stability for both anode and cathode materials because of increased active sites, enhanced reaction kinetics and CO- poison tolerance dues to single-solid solution as compared to conversional PGMs alloys. Both the electrochemical and physicochemical priorities affect the efficiency of energy conversion and storage. The future work following this trend is the consideration of "giant" HEAs compounds. Furthermore, the overall findings therefore not only depict the use of metal hydrides as anode materials but also as solid-state electrolytes. Beyond the conventional Ni-MHy battery, the potential of these hydrides has been demonstrated at a lab-scale upon optimization of a range of innovative energy storage concepts, including the MgH2-Li chemistry. Extensive research however still needs to be conducted to promote the development of new batteries of higher energy density and lower cost. Computer modeling demonstrates a better approach to understanding the interfacial electrochemical properties and physico-chemical properties. In addition, the efficiency of the electrochemical systems was well predicted machine learning through artificial neural networks, which shows the efficient potential approach to predict the efficiency of fuel cell, hydrogen storage and batteries. Among the algorithm approach, the differential evolution utilizing the single hidden layer shows the efficient and electrocatalytic reaction kinetics prediction. The modeling of structural formation and electrochemical properties of metal hydrides, high entropy and MOFs should be mandatory to strengthen the synthesis and better understanding of electrocatalysts. Although advances centred on solving energy problems have soared

with the discovery and implementation of various emerging catalysts, further work still needs to be conducted to ensure sustainable energy systems and technologies. In addition to high efficiency, catalysts for energy generation and storage should result in technologies that are affordable, abundant and generate clean energy.
