Water splitting involves a hydrogen evolution reaction (HER) at the cathode and an oxygen evolution reaction (OER) at the anode, and OER has been considered as the major bottleneck for water splitting due to the sluggish reaction kinetics and high OO bond formation energy barrier caused by its four-electron coupling process. [2][3][4][5] Designing the external-and internal structure of electrocatalysts is fundamental to achieve high catalytic activities at low overpotential and equally important to the electrocatalysts themselves, the reaction efficiency also strongly depends on the mass transfer outside the electrode surface and electron transfer inside the electrode structure. [4][5][6] The mass transfer at the interfaces between the catalyst and electrolyte is responsible for the immediate supplying of electrolytes (and reactants) and associated with rapid release of bubbles generated by the reactions (O 2 gas, for the case of OER). [7] The kinetics of mass transfer as the rate-controlling step, therefore, govern the efficiency of the electrochemical reaction, by taking much larger time constant compared with that of the electron transfer. [8,9] For gas-evolving electrochemical system, bubbles may adhere to the catalyst's surface and block the active sites by forming bubble froth layers. This process

The slow oxygen evolution reaction (OER) limits water splitting, and external fields can help improve it. However, the effect of a single external field on OER is limited and unsatisfactory. Furthermore, the mechanism by which external fields improve OER is unclear, particularly in the presence of multiple fields. Herein, we propose a strategy for enhancing the OER activity of a catalyst using the combined effect of an optical‐magnetic field and study the mechanism of catalytic activity enhancement. Under the optical‐magnetic field, Co3O4 reduces the resistance by increasing the catalyst temperature. Meanwhile, CoFe2O4 further reduces the resistance via the negative magnetoresistance effect, thus decreasing the resistance from 16 Ω to 7.0 Ω. Additionally, CoFe2O4 acts as a spin polarizer, and electron polarization results in a parallel arrangement of oxygen atoms, which increases the kinetics of the OER under the magnetic field. Benefiting from the optical and magnetic response design, Co3O4/CoFe2O4@Ni foam requires an overpotential of 172.4 mV to reach a current density of 10 mA·cm−2 under an optical‐magnetic field, which is significantly higher than those of recently reported state‐of‐the‐art transition‐metal‐based catalysts.This article is protected by copyright. All rights reserved

The sluggish kinetics of oxygen evolution reaction (OER) remains a bottleneck for the electrocatalytic water splitting. In addition to improving the intrinsic activity of electrocatalysts, the electrode structure and external environment also have a significant influence on catalytic performance. Inspired by photosynthesis in plant leaves, a photothermal conversion strategy is proposed via the decoration of photothermal responsive MoS2/FeCoNiS‐nanotube (MoS2/FeCoNiS‐NT) on designed through‐hole porous nickel foam (PNF), defined as MoS2/FeCoNiS‐NT@PNF, to boost OER performance. The PNF facilitated bubble transport in OER by mimicking stomata structure of the leaf, and simultaneously, the MoS2/FeCoNiS‐NT increases light absorption and photothermal conversion by simulating the leaf epidermis. Benefiting from bionic structure and functional design, the MoS2/FeCoNiS‐NT@PNF electrode exhibits highly effective oxygen‐evolving ability and excellent photothermal conversion capacity (surface temperature: 25 °C → 52.3 °C, AM1.5G), which increases the intrinsic activity of electrocatalysts. With the assistance of optimized electrode structure and the photothermal effect, the MoS2/FeCoNiS‐NT@PNF electrode exhibits a low overpotential of 214 mV to achieve 50 mA cm−2. This research reveals that tuning the electrode structure can promote light absorption in the electrolyte in favor of OER performance, which can serve as an inspiration for the development of high‐performance catalytic electrodes.