Atomic metal‐modulated heterostructures have been evidenced as an exciting solution to develop high‐performance multifunctional electrocatalyst toward water splitting. In this research, a catalyst of continuous cobalt‐cobalt oxide (Co‐CoO) lateral heterostructures implanted with well‐dispersed rhodium (Rh) atoms and shelled over conductive porous 1D copper (Cu) nano‐supports for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in both freshwater and seawater under alkaline condition is proposed. It is found that synergistic effects coming from uniform Rh atoms at doping level and Co‐CoO heterostructures afford rich multi‐integrated active sites and excellent charge transfer, thereby effectively promoting both HER and OER activities. The material requires overpotentials of 107.3 and 137.7 mV for HER and 277.7 and 260 mV for OER to reach an output of 10 mA cm−1 in freshwater and mimic seawater, respectively, surpassing earlier reported catalysts. Compared to a benchmark a Pt/C//RuO2‐based two‐electrode electrolyzer, a device derived from the 1D‐Cu@Co‐CoO/Rh on copper foam delivers comparable cell voltages of 1.62, 1.60, and 1.70 V at 10 mA cm−2 in freshwater, mimic seawater, and natural seawater, respectively, together with robust stability. These results evidence that 1D‐Cu@Co‐CoO/Rh is a promising catalyst for green hydrogen generation via freshwater and seawater electrolysis applications.

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In this work, we used an interfacial engineering method to investigate a novel hybrid of two-dimensional cobalt sulfide-Mxene (2D CoS-Mo2TiC2) heterostructure supported by a three-dimensional foam substrate. The modification electronic properties caused by unique interfacial interactions resulted in a significant increase in the number of electroactive sites and charge transfer ability, thereby accelerating kinetics of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in an alkaline medium. The catalyst required overpotential of 248.2 and 310 mV at a current response of 50 mA cm-2 for HER and OER, respectively, along with a remarkable stability. In addition, a two-electrode electrolyzer derived from the developed 2D CoS-Mo2TiC2 catalyst showed a cell voltage of 1.74 V at 10 mA cm-2 and a good stability during 25 h continuous operation. The achieved results were associated to the formation of a unique interfacial heterostructure with the strong interaction between two material phases, which effectively modified electronic structure and surface chemistry, thereby leading to the enhancement of catalytic performance. The study offered a potential route to synthesize new catalyst for green hydrogen production via water splitting.

Development of multifunctional electrocatalysts with high efficiency and stability is of great interest in recent energy conversion technologies. Herein, a novel heteroelectrocatalyst of molecular iron complex (FeMC)‐carbide MXene (Mo2TiC2Tx) uniformly embedded in a 3D graphene‐based hierarchical network (GrH) is rationally designed. The coexistence of FeMC and MXene with their unique interactions triggers optimum electronic properties, rich multiple active sites, and favorite free adsorption energy for excellent trifunctional catalytic activities. Meanwhile, the highly porous GrH effectively promotes a multichannel architecture for charge transfer and gas/ion diffusion to improve stability. Therefore, the FeMC–MXene/GrH results in superb performances towards oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) in alkaline medium. The practical tests indicate that Zn/Al–air batteries derived from FeMC–MXene/GrH cathodic electrodes produce high power densities of 165.6 and 172.7 mW cm−2, respectively. Impressively, the liquid‐state Zn–air battery delivers excellent cycling stability of over 1100 h. In addition, the alkaline water electrolyzer induces a low cell voltage of 1.55 V at 10 mA cm−2 and 1.86 V at 0.4 A cm−2 in 30 wt.% KOH at 80 °C, surpassing recent reports. The achievements suggest an exciting multifunctional electrocatalyst for electrochemical energy applications.

Successful development of an electrocatalyst capable to promote the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) elements of water electrolysis is desirable for green hydrogen gas production. Herein, this work designs intermolecular metallic single‐site complexes of iron phthalocyanine (FePc) and vanadium oxide phthalocyanine (VOPc) dually immobilized on 3D hierarchical MoS2‐coated MXene Mo2TiC2Tx (MX/MoS2) heterostructures as a high‐performance bifunctional electrocatalyst. The well‐organized structure with an unusual coordination environment and electronic localization impressively enhances water adsorption and activation to remarkably accelerate HER and OER kinetics. Therefore, the hybrid material requires overpotentials as small as 17.4 and 300 mV to drive 10 mA cm−2 for the HER and 50 mA cm−2 for the OER in 1.0 m KOH media, respectively. The electrolyzer of MX/MoS2‐FePcVOPc(+,−) exhibits low cell voltage of only 1.45 V to reach a current response of 10 mA cm−2 in 7.0 m KOH at 75 °C along with excellent current retention stability of 99%/94% after long‐term operations of 30 h at 10/50 mA cm−2. Moreover, a solar‐to‐hydrogen conversion efficacy of 19.96% is achieved in a solar energy‐powered water electrolysis system, highlighting the great potential of the developed MX/MoS2‐FePcVOPc electrocatalyst toward water electrolysis.