Intermolecular Metallic Single‐Site Complexes Dispersed on Mo₂TiC₂T_x/MoS₂ Heterostructure Induce Boosted Solar‐Driven Water Splitting

Abstract

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.

High-performance artificial leaf: from electrocatalyst design to solar-to-chemical conversion

“…Tran et al combined two kinds of metallic single-site complexes, i.e., iron phthalocyanine (FePc) and vanadium oxide phthalocyanine (VOPc) which had an unsaturated-coordinated site and a unique electronic structure. 97 The interaction between metal-phthalocyanine sites and MX/MoS 2 base by strong metal-S bonding induced electronic reconfiguration and distribution to appropriately regulate the energy barrier and adsorption/ desorption, leading to a low operating voltage of 1.45 V to reach 10 mA cm À2 in 7 M KOH at 75 1C and only slight attenuation of current density (is 1% of 10 mA cm À2 ) for a continuous operation of 30 h, further driven by a solar cell panel, and the system achieved an STH efficiency of 19.96% under 1 sun irradiation in 7 M KOH at 75 1C.…”

Cr doping and heterostructure-accelerated NiFe LDH reaction kinetics assist the MoS2 oxygen evolution reaction

“…29 Similarly, Tran's team immobilized intermolecular metal unit complexes of iron phthalocyanine and vanadium oxide phthalocyanine on a three-dimensional multilevel MoS 2 -coated MXene Mo 2 TiC 2 Tx heterostructure. 30 Due to the unique coordination environment and electronic localization they were able to achieve, water adsorption and activation were improved, greatly increasing the kinetics of the HER and OER. Although these preceding studies confirmed the contribution of heterostructure construction to improving the electrocatalytic performance of MoS 2 , the advantages of MoS 2 's excellent electrical conductivity and ultrathin layered structure have not yet been fully utilized, resulting in its catalytic performance remaining lower than expected.…”

Design of Ti3C2Tx/SnO2-Selective Ethanolamine Sensor

“…The dominant synthesis methods for MXenes are wet chemical etching and electrochemical etching. − Common etching agents are HF, LiF/HCl or NaF/HCl mixtures, ammonium hydrogen fluoride, and so on. For the HF etchant, H + cations serve as oxidants, and F – anions act as the ligand to combine with byproducts of the reaction. − The HF etching is easier to obtain the “accordion-like” multilayered MXene Ti 3 C 2 T x.…”