Enhancing the photocatalytic efficiency of sunlight-driven hydrogen generation in MnO2 through Mg2+ doping

Low-cost techniques for hydrogen production are crucial to mitigate the depletion of energy fuel reserves. Therefore, the development of optically active catalysts in the visible region offers an opportunity for water photo-reduction. Indeed, hydrogen has garnered a significant interest as a green and efficient energy source and its formation by water splitting is a promising route to store energy; its photocatalytic production offers a renewable and environmentally friendly alternative to fossil fuels. This underscores the critical importance of optimizing the efficiency of photocatalysts, co-catalysts, and sacrificial agents. In this study, we synthesized Nano-particles of MnO2 and doped with magnesium (X%Mg/MnO2; X = 2.5, 5 and 10%) by co-precipitation. The oxides were synthesized by a simple and low-cost procedure and characterized physically. X-ray diffraction (XRD) revealed that X%Mg/MnO2 exhibit single phases, crystallizing in the rutile structure. Moreover, the introduction of Mg2+ into MnO2 led to a moderate reduction in their crystallite size. The semiconductors Mg2+-doped MnO2 were subsequently employed as photocatalysts for the H2 production under solar illumination. The MQ-8 sensor, specifically designed to measure hydrogen concentrations between 100 and 10,000 ppm, was used to quantify the amount of H2 gas generated by photocatalysis. The study revealed that increasing the Mg2+-content significantly improved the photoactivity, leading to a substantial H2 evolution rate of 506.67μmol.h−1.g−1, 4.7 times higher than that of undoped MnO2, highlighting the excellent performance of Mg2+-doped MnO2. This study proposes a viable concept to develop and promote cost-effective photocatalysts in green hydrogen, bringing new impetus on the photocatalytic properties of Mg-doped oxide.