Amorphous boron 1 Bi-functional 1 Bifunctional photocathode 1 Durability 1 Efficiency 1 Extra-long durability Field emission cathodes 1 Higher efficiency 1 Li–O2 batteries 1 Li–O2 battery 1 Nanosheets 1 Overpotential 1 Photo-assisted 1 Photocathodes 1 Round trip 1 Round-trip efficiency 1 bifunctional photocathodes 1 boron 1 extra-long durability 1 round-trip efficiencies 1