A Dual Photoelectrode Photoassisted Fe–Air Battery: The Photo‐Electrocatalysis Mechanism Accounting for the Improved Oxygen Evolution Reaction and Oxygen Reduction Reaction of Air Electrodes

Abstract

Seeking advanced energy conversion devices, which are sustainable as well as environment friendly, is extremely challenging in our modern society. [3,4] In this regard, the metal-air battery is among the alternative costeffective battery technologies with high energy density, environmentally friendly, and which is composed of an air electrode and a metal electrode, generating electricity through the redox reaction. [5] Among the various metal-air batteries, Li-air and Zn-air batteries have received the most extensive attention. [6] Although Li-air battery exhibits extremely high theoretical energy density (3500 Wh kg −1 ), Li is so reactive that the Li-air battery inevitably faces security risks. [7,8] Iron (Fe) is the fourth most abundant element in the world. In addition, Fe is also a cheap, safe, and environmentally friendly anode material for metal-air batteries. [9] Therefore, compared with the Zn anode, Fe as the anode can reduce battery cost for its abundant reserves. [10] The Fe-air battery has been considered as a low-cost, environmentally benign electrochemical energy-storage system. [11][12][13] Fe-air battery can sustain more charge-discharge cycles than Zn-air battery due to its lower susceptibility to dendrite formation. [8] Intrinsically, the Fe-air battery can store/ release energy repeatedly as needed via oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) but this process is always plagued by slow kinetics of OER/ORR. [14] Therefore, the study on improving reaction kinetics or lowering overpotential of OER/ORR has garnered considerable research interest in recent years. [5,15] Yu et al. used IrO 2 /Ti as the electrode of Fe-air battery to reduce the overpotential of OER and it can achieve a charge voltage of 1.65 V at 1 mA cm −2 . [12] To further reduce the OER/ORR overpotential of metal-air battery, the combination of solar energy and battery is a new research field with fascinating prospects. [16] Solar energy has been utilized in various electrochemical devices for improved reaction kinetics and lowered overpotential, such as hydrogen evolution reaction, water spilling, and pollutant degradation. [17][18][19][20][21] For the aqueous metal-air battery, it usually involves a semiconductor that, upon illumination, could generate Effective utilization of solar energy in battery systems is a promising solution to achieve sustainable and green development. In this work, a photoassisted Fe-air battery (PFAB) with two photoelectrodes of ZnO-TiO 2 heterostructure and polyterthiophene (pTTh)-coated CuO (pTTh-CuO) grown on fluorinedoped tin oxide (FTO) is proposed. The band structure of semiconductors and the charge-transfer mechanism of heterostructure are studied. The electrochemical results show that the photogenerated electrons and holes play key roles in reducing the oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) overpotential in the discharging and charging processes, respectively. The short-circuit current density, the open-circuit voltage, and the maximum power outpu...

Photo‐Assisted Metal‐Air Batteries: Recent Progress, Challenges and Opportunities

“…CuO photoelectrodes were employed for separated photoelectrodes. [70] This photo-assisted FeÀ O 2 battery achieved a low charging voltage of 0.64 V and a high discharging voltage of 1.38 V at 0.1 mA cm À 2 under illumination. As presented above, the photo-assisted strategies were viable to promote performances in current metal air battery systems.…”

“…As for the Fe−O 2 battery, the photo‐assisted strategies were also applicable with proper photoelectrode constructions. The ZnO‐TiO 2 and pTTh‐CuO photoelectrodes were employed for separated photoelectrodes [70] . This photo‐assisted Fe−O 2 battery achieved a low charging voltage of 0.64 V and a high discharging voltage of 1.38 V at 0.1 mA cm −2 under illumination.…”

Integrated Photovoltaic Charging and Energy Storage Systems: Mechanism, Optimization, and Future

“…[85][86][87] To address this issue which are promising solutions to the dilemma of low photon absorption efficiencies, including narrowing the bandgap and controlling the surface morphology of materials (nanophotonic structures). [39,88,89] For instance, for wide bandgap photoelectrode materials, it is one of the most commonly used methods to enhance the optical absorptivity by doping elements into the photoelectrode to adjust the band structure of the photoelectrode. [73,79] Makldis et al reported nitrogen (N)-doped TiO 2 powder samples, which were used as photoelectrodes in DSSCs (Figure 6b).…”

“…Compared with connecting high-cost photovoltaic and battery modules, SPRBs store solar energy by driving nonspontaneous reversible redox reactions in PEC cells through photoelectrode materials. [89,163,164] And delivering energy through reverse electrochemical reactions in the same device is much more cost-effective. [165,166] In order to obtain high conversion efficiency and high durability, photoanode with suitable energy level (energy level matching) needs to be considered when designing integrated photoelectrodes to meet the requirements (light harvesting efficiency and charge separation efficiency) of different devices.…”

Conformal Lithium Peroxide Growth Kinetically Driven by MoS2/MoN Heterostructures Towards High‐Performance Li−O2 Batteries

“…To overcome this limit, heterostructure construction by coupling two different functional moieties through interfacial engineering has been proposed as an effective strategy. [21][22][23] In this vein, a diversity of heterostructures comprising NiS 2 /ZnIn 2 S 4 , TiO 2 -Fe 2 O 3 , and NiCo 2 S 4 @NiO etc. have been introduced and shown to work well in catalyzing the reversible formation/decomposition of Li 2 O 2 in LiÀ O 2 batteries, improving both the Coulombic and round-trip efficiencies.…”