Graphene oxide (GO) contains randomly distributed nonconductive sp3-C domains with planar acidity, making it simultaneously an electrical insulator and a proton conductor. GO’s ability for in-plane and through-plane cationic transport together with its impermeability to molecular fuels projected them as inexpensive and sustainable membranes for proton exchange membrane fuel cells (PEMFCs). Nevertheless, the room-temperature proton transport in bulk GO is at least an order lower than that of the state of the art Nafion membrane, challenging the construction of a practical energy conversion device with the former. We show that the proton flux in GO along the H-bonded network projected outward of the carbon planes can be significantly amplified by thinning the 2D carbon layer stacking of carbon nanosheets in GO. The noticeably higher room-temperature fuel cell performance metrics of a thin-layer GO proton conductor compared to the commercial Nafion membrane with ∼410 mW/cm2 of peak power at ∼1300 mA/cm2 of peak current demonstrates distinct progress in the sustainable energy landscape.

Interconversion of acid-base neutralization energy as electrical driving force can spontaneously desalinate saline water during electric power production without a net redox reaction. This entropically favorable chemistry performs desalination by reversible redox reactions involving only gases, water, H + , and OH À such that the products and reactants of the reaction will not contaminate the desalinated water.

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Here we show a surrogate strategy for power production, wherein light is used to actuate a discharge chemistry in the cathode of an aqueous rechargeable battery (ARB). The proposed photo battery consists of a titanium nitride photoanode, promising cathode material iron(III) hexacyanoferrate(II) as the battery active species and Na 2 S 2 O 8 as the chemical charging agent. The photo battery delivered negligible capacity in the dark and the capacity shot up to 77.8 mAh/g when artificially shined light, confirming that the battery chemistry is light driven. In the ambient light, the device retained 72% of its artificial light discharge capacity with a stable cycling for more than 100 cycles. Further, an unprecedented means for charging the battery rapidly is presented using Na 2 S 2 O 8 and it revitalized the battery in 30 s without any external bias. This methodology of expending a photoanode extends to a battery that is free from dissolution of active materials, irreversible structural changes, spontaneous deinsertion reactions, and safety concerns commonly encountered in the state of the art anode materials in ARBs. Apart from bringing out a sustainable way for power production, this device opens up avenues for charging the battery in the likely events of electrical input unavailability, while solving the critcial issues of longer charging time and higher charging voltage.