Decorating Cd_0.9Zn_0.1S Using a Magnetic FeCo@ N-Doped Graphite Carbon Layer to Achieve Considerable Hydrogen Evolution Efficiency

Abstract

Photocatalytic hydrogen production technology has emerged as one of the most promising technologies to address the future energy crisis. Cd0.9Zn0.1S (CZS) is a promising photocatalyst for visible light activation but is limited by the slow kinetics of photoexcited carrier separation. Density functional theory (DFT) calculations based on first-principles showed that the introduction of a cocatalyst, N-doped graphite carbon (FC@NC), could effectively reduce the adsorption free energy of hydrogen, thus accelerating the hydrogen reaction kinetics of CZS. Supported by theoretical predictions, magnetic FC@NC nanoparticles were successfully prepared by precipitation and calcination and then combined with tetrapod CZS by ultrasonic self-assembly and calcination to form the FC@NC/CZS composite photocatalyst with Schottky contact. The FC@NC/CZS composite photocatalyst with the best mass ratio of FC@NC proved a considerable photocatalytic hydrogen evolution rate up to 79.9 ± 0.1 mmol g–1 h–1 under visible light exposure, which was 4.4 ± 0.1 times that of pristine CZS, and the apparent quantum efficiency (AQE) at 450 nm was as high as 52%. Finally, based on the experimental results and DFT calculations, a possible mechanism for the enhanced photocatalytic activity of FC@NC/CZS composites with the Schottky heterojunction was first proposed. In general, we attribute the boosted and stable photocatalytic property of FC@NC/CZS photocatalytic performance to the following three aspects: (1) the bimetallic alloy cocatalyst easily acts as an electron collector, (2) the graphite carbon layer protects the alloy from oxidation, and (3) the nitrogen-doped carbon layer provides more active sites for the reaction. This work provided a green and economical technique for an efficient hydrogen evolution reaction using light energy in the environment.