Sunlight induced efficient photocatalytic oxidation of benzylamines and CO2 reduction over a 2D–2D MoS2/FP-BTA heterojunction catalyst

Abstract

The photocatalytic production of fuels and chemicals utilizing highly effective catalysts has garnered a lot of interest as a sustainable and clean strategy. Herein, we have reported the effective fabrication of an imine-linked covalent organic framework, FP-BTA COF, supported 2D–2D MoS₂/FP-BTA heterojunction with molybdenum sulfide (MoS₂) utilizing an easy hydrothermal technique. The development of a 2D–2D heterojunction between a covalent organic framework (COF) and molybdenum sulfide (MoS₂) with well-matched band positions can efficiently restrict the recombination of the charge carriers and boost the light absorption capacity along with the surface area, which is mainly responsible for the greatly improved catalytic efficiency. This as-prepared MoS₂/FP-BTA hybrid photocatalyst demonstrated exceptional dual catalytic efficiency for the oxidative coupling of benzylamine derivatives to generate higher yields (92%) of N-benzylidene benzylamines along with selective reduction of carbon dioxide (CO₂) to formic acid (highest generation rate = 43.3 mol g_cat⁻¹ h⁻¹) at atmospheric carbon dioxide (CO₂) pressure as compared to molybdenum sulfide (MoS₂) and the FP-BTA COF without the requirement of any extra sacrificial electron donors under sunlight. The present research also focuses on economically viable, straightforward and sustainable methods for visible-light induced oxidation of a sequence of benzylamines under atmospheric oxygen (O₂) utilizing the MoS₂/FP-BTA hybrid material and the highest 98% isolated yield of the product containing a mixture of the corresponding imine and carbonyl compounds was achieved under ambient reaction conditions. The photocatalyst produced a good amount of the intended products and was easily recoverable and recyclable up to the fifth run for both reactions. The creation of a single hybrid with a 2D–2D interface by fusing organic and inorganic materials as well as the twin strategy of producing valuable chemicals in a single process may open up new prospects for sustainable development and enhance the atom economy.