The evolution of photocatalytic H2 is an interesting way to generate H2 and a graphene oxide on way to overcome the threat of an energy crisis. Despite the many efforts that have been devoted to the development of a highly efficient photocatalyst, the practical application of the H2 evolution rate is still unsatisfactory, this is mainly due to the fast recombination of photogenerated carriers. In one of the newest approaches, heterojunction construction is widely adopted due to its efficiency in facilitating the separation of photogenerated electron-hole pairs and flexibility in material selection [1]. The development of efficient semiconductor composites utilizing visible light for renewable energy production is highly desirable. In many studies to date, many semiconductor materials are used to synthesize photocatalysts that are most suitable and efficient for H2 production under solar irradiation, such as metal oxides, metal selenides, metal sulfides, metal-organic frameworks, and carbon-based materials commonly used in water photolysis [2–5]. Graphene oxide (GO) has recently attracted considerable attention in the field of energy conversion and environmental improvement due to its distinct advantages such as high conductivity, environmental friendliness, excellent solubility, and chemical inertness [6]. In particular, the formation of band gap energy of graphene oxide can be tuned in a wide energy range by controlling the size or functionality of the energy region, so it can be applied as a semiconductor with narrow gap energy for photocatalytic application.
In addition, it has been reported that the combination of GO and TiO2 shows improved photocatalytic performance in the field of H2 evolution and decomposition of pollutants [7, 8]. GO, a photocatalyst in the graphene oxide-TiO2 heterojunction, generally acts as a photoabsorbent or photo-sensitive agent to maximize photoelectron emission, and acts as an electron acceptor to receive photoelectrons generated from TiO2 to induce efficient charge separation. However, despite its practical superiority, photocatalytic activity for graphene oxide-TiO2 binary photocatalysts under visible light irradiation was not significantly improved for these effects due to the limited ability of graphene oxide to absorb visible light. [9, 10]. To date, many semiconductors with wide visible-light utilization have been explored for hydrogen generation including CdS, ZrO2, BaTi4O9, ZnNb2O6 ternary ZnIn2S4 materials, and polymer composite. However, their wide application is restricted by many factors, including toxicity, photo-corrosion behavior, and poor photocatalytic efficiency. The construction of a non-toxic, inexpensive, and visible-light responsive photocatalyst for hydrogen evolution remains an urgent and challenging topic. In attempting to overcome these limitations, we try to synthesize multi-component metal sulfide with a tunable band gap and band gap alignment by controlling the composition. Recently, Mariia et al. also reports on the integration of CsPbBr3 on g-C3N4 nanosheets to construct composite photocatalysts [11]. These works have revealed that a well-designed chemical bonded interface in the heterojunction is beneficial for the photocatalytic process. They found that the chemical bonded interface with extensive areas facilitates the migration of carriers across the junction. Our previous work, BaCuZnS-G-TiO2 (BCZS-G-T) showed that Ba,and Zn containing compound with graphene oxide has high hydrogen evolution efficiency under visible-light irradiation for H2 production reaction [12]. For a single conductive or semiconductor material, it is hard to fulfill all demands like cost effective, low bandgap effect and efficient photocatalytic hydrogen evolution. Thus, our study point is to make efficient short-rod type catalyst to for hydrogen evolution [10, 13, 14]. Other issue is implementing graphene oxide with other TiO2, due to the low band gap of graphene oxide and good catalytic activity of TiO2. The preparations of graphene oxide based composite nano-composites are convenient and the obtained products are usually more stable than isolated particles. Most importantly, the intimately bonded graphene oxide/TiO2 surface promotes the separation of the photogenerated electrons and holes, and absorbs a wide range of incident light, thus enhances the photocatalytic performance [15, 16].
In this study, an ultrasonication method was used to synthesize BaNiSn-graphene oxide with a mesoporous TiO2 (BaNiSn-GT) serving as a co-catalyst for H2 evolution. We also investigate the photoelectrochemical properties of pure BaNiSn, BaNiSn-G, and BaNiSn-GT, as well as the effects of the most relevant sacrificial hole scavenger on the photocatalytic H2 evolution performance. Compared to pure BaNiSn and BaNiSn loaded with graphene oxide, the BaNiSn-GT composite exhibits remarkably improved performance in the evolution of photocatalytic H2. As the loading amount of BaNiSn-graphene oxide with TiO2 increased, the H2 generation rate under visible light irradiation (θ > 420nm) increased by about 2.5 times compared to the pure BaNiSn sample. Improved photocatalytic activity can be attributed to the synergistic effect of BaNiSn and graphene oxide-TiO2, where graphene oxide acts as an electron acceptor and medium, while BaNiSn provides an active site for H2 production. We hope that this work can contribute to the design and construction of highly efficient visible light-responsive photocatalysts for sustainable energy harvesting and transition.