Potassium ions intercalated into g-C3N4-modified TiO2 nanobelts for the enhancement of photocatalytic hydrogen evolution activity under visible-light irradiation

Abstract

Solar-to-chemical energy conversion is a challenging photochemical reaction for renewable energy storage. In recent decades, photocatalytic H2 evolution has been studied extensively. TiO2 is a well-established semiconductor in the field of photocatalytic H2 production; however, its low efficiency for solar energy utilization, and high photocarrier recombination rate, restrict its photocatalytic efficiency. Here, a series of K-intercalated g-C3N4-modified TiO2 nanobelts (TCN–Kx) with different dosages of K atoms were fabricated using a hydrothermal method followed by a calcination process. XRD, TEM and XPS tests indicate that a tight interfacial connection is formed between K–g-C3N4 and the TiO2 nanobelts. DFT calculations indicated that K dopants prefer to be at the interlayer sites of g-C3N4, suggesting increased charge transfer efficiency. The H2 production efficiency of the TCN–Kx composite materials from water splitting under visible-light irradiation was clearly improved. Steady fluorescence spectroscopy and photocurrent measurements confirmed that the improvement in photocatalytic H2 production activity was due to the superior charge separation and electron transfer efficiency of TCN–Kx composite materials.