A review on process design and bilayer electrolyte materials of bipolar membrane fuel cell by Sayed Daud, Syarifah Noor Syakiylla, Jaafar, Juhana, Mohd. Norddin, Muhammad Noorul Anam, Sudirman, Rubita, Onuomo, Oseh Jeffrey, Ismail, Ahmad Fauzi, Othman, Mohd. Hafiz Dzarfan, Rahman, Mukhlis A., Alias, Nur Hashimah, Junoh, Hazlina