SrTiO3 Photocatalyst Research Articles

Insight of SrCl2 as an Appropriate Flux Medium in Synthesizing Al-Doped SrTiO3 Photocatalyst for Overall Water Splitting

Insight of SrCl2 as an Appropriate Flux Medium in Synthesizing Al-Doped SrTiO3 Photocatalyst for Overall Water Splitting

EPR study of charge separation associated states and reversibility of surface bound superoxide radicals in SrTiO3 photocatalyst

Understanding the processes of charge generation, transfer and capture is important for the design and synthesis of efficient photocatalysts. In this work, light-induced charge separation and effect of O2 on electron transfer processes in SrTiO3 were investigated by electron paramagnetic resonance (EPR). It was found that photoinduced electron transfer from O2− to Ti4+ produced Ti3+ and O− redox radical pairs under vacuum condition. Under oxygen atmosphere, however, surface bound superoxide radicals O2− were formed by electron reduction of adsorbed oxygen at initial photoirradiation stage, and quenched by the reverse electron transfer to Ti4+ upon further photoirradiation. Formation of long-lived charge separation associated [Ti3+---O−] species and the reversibility of surface bound superoxide radicals mediating the processes of photogenerated electrons may be accountable for the high activity of SrTiO3 in photocatalytic water splitting reaction.

Development of Direct Z-Schemes 2d/2d Bi2o2co3/ Srtio3 Photocatalyst with Interfacial Interaction for Photocatalytic Co2 Reduction

Development of Direct Z-Schemes 2d/2d Bi2o2co3/ Srtio3 Photocatalyst with Interfacial Interaction for Photocatalytic Co2 Reduction

Enhanced Water Splitting into H2 and O2 Over Edta Treated Srtio3 Photocatalysts with High Crystallinity, Reduced Size and Surface Nanostructure

Enhanced Water Splitting into H2 and O2 Over Edta Treated Srtio3 Photocatalysts with High Crystallinity, Reduced Size and Surface Nanostructure

Carrier recombination in SrTiO3 single crystals: impacts of crystal faces and Nb doping

We observed the carrier recombination in SrTiO3 single crystals with several crystal faces and Nd doping concentrations using time-resolved photoluminescence and microwave photoconductivity decay methods. The shapes of the decay curves were independent of the excited carrier concentrations, and thus the carriers recombined through the Shockley–Read–Hall and surface recombination processes. From the measurements for different crystal faces, we found that, although the surface recombination is significant for the (100), (110), and (111) faces, they have similar surface recombination velocities of ∼106 cm s−1. Therefore, as photocatalysts, the shape of the materials has a minor effect on the energy conversion efficiency. Based on the dependence of the Nb doping concentration, a high doping concentration significantly enhances the carrier recombination, whereas a moderate Nb doping induces only a slight reduction in the time constants of the carrier decay. In addition, the time constant increases with temperature, and thus moderate Nb doping will have a positive effect on the energy conversion efficiency of SrTiO3 photocatalysts at high temperatures.

(Invited) Theoretical and Experimental Performance Metrics of Doped SrTiO3 Photocatalyst Particles for Visible-Light-Driven H2 Evolution

Solar hydrogen production could be a techno-economically viable alternative to steam methane reforming through development of new reactor designs and reaction schemes. Motivated by this fact, my group recently proposed a dual-bed batch reactor for Z-scheme solar water splitting that consists of stacked photocatalyst beds, which aid performance due to serial light absorption and short distances for redox shuttle mass transport. An unexpected discovery based on this design is that an ensemble of optically thin materials is more beneficial to theoretical solar-to-hydrogen conversion efficiencies than a standard single-light-absorber geometry. Through parallel experimental work we have shown that state-of-the-art doped and codoped SrTiO3 H2-evolving photocatalyst particles exhibit variability in homogeneity of dopant distributions, which correlates to overall performance. We have also observed that nanoscale coatings enable selective H2 evolution and desired redox shuttle reactivity over undesired reactions, which theoretically enable increased solar-to-hydrogen conversion efficiencies. Collectively these results provide new design guidelines and additional research pathways for the development of effective composite materials to serve as active components in techno-economically viable solar fuels devices.

Direct confirmation of the dopant site in indium-doped SrTiO3 photocatalyst via atomic-scale analytical transmission electron microscopy imaging

Confirming the dopant site of In3+-doped SrTiO3 (In–STO) is essential to reveal the mechanism of its photocatalytic activity. In a previous study, x-ray absorption spectroscopic analysis and theoretical investigations were performed to discuss the dopant site, and In3+–Ti4+ substitution was proposed. However, direct confirmation of the In3+ dopant site has not yet been reported. Here, we performed direct atomic-scale imaging of In–STO crystals via analytical transmission electron microscopy and revealed the dopant site based on real-space elemental mapping. The Ti and Sr sites in the SrTiO3 crystal lattice were well identified by atomic column elemental mapping using energy dispersive x-ray spectroscopy (EDS). The EDS signal of indium has a stronger intensity at the Ti site than at the Sr site, based on the total analysis of each Ti and Sr atomic column. By applying principal component analysis on the raw EDS spectral imaging data cube, the indium site was clearly imaged; it completely fit into the Ti atomic column positions. These results provide direct evidence of In–Ti substitution in In-STO photocatalysts.

Linking in situ charge accumulation to electronic structure in doped SrTiO3 reveals design principles for hydrogen-evolving photocatalysts.

Recently, high solar-to-hydrogen efficiencies were demonstrated using La and Rh co-doped SrTiO3 (La,Rh:SrTiO3) incorporated into a low-cost and scalable Z-scheme device, known as a photocatalyst sheet. However, the unique properties that enable La,Rh:SrTiO3 to support this impressive performance are not fully understood. Combining in situ spectroelectrochemical measurements with density functional theory and photoelectron spectroscopy produces a depletion model of Rh:SrTiO3 and La,Rh:SrTiO3 photocatalyst sheets. This reveals remarkable properties, such as deep flatband potentials (+2 V versus the reversible hydrogen electrode) and a Rh oxidation state dependent reorganization of the electronic structure, involving the loss of a vacant Rh 4d mid-gap state. This reorganization enables Rh:SrTiO3 to be reduced by co-doping without compromising the p-type character. In situ time-resolved spectroscopies show that the electronic structure reorganization induced by Rh reduction controls the electron lifetime in photocatalyst sheets. In Rh:SrTiO3, enhanced lifetimes can only be obtained at negative applied potentials, where the complete Z-scheme operates inefficiently. La co-doping fixes Rh in the 3+ state, which results in long-lived photogenerated electrons even at very positive potentials (+1 V versus the reversible hydrogen electrode), in which both components of the complete device operate effectively. This understanding of the role of co-dopants provides a new insight into the design principles for water-splitting devices based on bandgap-engineered metal oxides.

One-step heating hydrothermal of iridium-doped cubic perovskite strontium titanate towards hydrogen evolution

A series of Iridium (Ir)-doped strontium titanate (SrTiO3) was successfully prepared for the first time by a one-step heating hydrothermal method for water splitting applications. An amount of Ir was incorporated into SrTiO3 structure at 210 °C and pH = 13 without any surfactant or stabilization addition. Compared to the pure SrTiO3 nanomaterials, the as-obtained Ir-doped SrTiO3 photocatalysts shows the significantly improved hydrogen evolution under ultraviolet irradiation and the highest activity with a hydrogen evolution rate of 1376 μmol.g−1.h−1 of the Ir-doped SrTiO3 photocatalyst with very low amount of doping Ir (1.0 wt%). The X-ray photoelectron spectroscopy (XPS) analysis confirms the existence of Ir4+ in accompany with Ir3+ on the surface, which could be assigned for the excellent performance of prepared materials. The successful synthesis of Ir-doped SrTiO3 not only introduces a new route to prepare a promoting material for hydrogenation evolution from water splitting under ultraviolet (UV) irradiation using methanol as a sacrificed agent, but also creates a preliminary step for high-performance Ir-doped SrTiO3.

Investigation on the highly active SrTiO3 photocatalyst toward overall H2O splitting by doping Na ion

Photocatalytic properties of SrTiO3 doped with Na ion (Na+-SrTiO3) were investigated to develop the photocatalyst exhibiting high photocatalytic performances, not only the activity but also the durability for overall H2O splitting. The photocatalytic activity was remarkably improved by the introduction of a small amount of Na ion into SrTiO3 photocatalyst using rhodium and chromium mixed oxide (Rh0.7Cr1.3O3) as the co-catalyst. Moreover, the photocatalytic activity was influenced by the purity of the raw materials used for preparing Na+-SrTiO3 photocatalyst rather than the properties that originated with the preparation methods. The apparent quantum yield (AQY) of overall H2O splitting was 28% under the irradiation at 365 nm over the optimal Rh0.7Cr1.3O3/Na+-SrTiO3 photocatalyst. The photocatalytic performances of Rh2-yCryO3/Na+-SrTiO3 were confirmed to be further improved by separating the hydrogen evolution reaction (HER) site and the oxygen evolution reaction (OER) site over the surface by co-loading CoOx co-catalyst as OER sites. The states of Na+ doped SrTiO3 was investigated to make clear the key factors in the enhancement of the photocatalytic activity by the doping of aliovalent ions.

Optimized Synthesis of Ag‐Modified Al‐Doped SrTiO3 Photocatalyst for the Conversion of CO2 Using H2O as an Electron Donor

AbstractAg‐modified Al‐doped SrTiO3 (Ag/Al‐SrTiO3) was fabricated via a flux method and was found to exhibit high efficiency and selectivity toward CO evolution using H2O as an electron donor under photoirradiation at wavelengths greater than 300 nm. The fabrication conditions, such as calcination temperature and time, were optimized in this study because these factors had obvious effects on the crystallinity, microstructure, and degree of Al doping of the Al‐SrTiO3 photocatalysts. The 1.0‐wt.% Ag/Al‐SrTiO3 photocatalyst fabricated by chemical reduction showed a good rate (5.5 μmol h−1) of CO formation. Moreover, excellent selectivity (98.8%) was achieved. Importantly, the O2 formation rate was 2.7 μmol h−1, which indicates that the number of estimated holes was equivalent to the number of electrons estimated from the CO formation rate. Thus, H2O is the electron donor in this case. In addition, the charge separation in SrTiO3 was significantly promoted after Ag modification and Al doping, and the Ag cocatalyst particle size and dispersion, as well as the chemical state of Ag, affected the photocatalytic activity.

Dye-sensitized SrTiO3-based photocatalysts for highly efficient photocatalytic hydrogen evolution under visible light

In this work, strontium titanate (SrTiO3)-based photocatalysts exhibited superior visible-light-driven photocatalytic hydrogen (H2) production activity by sensitization with xanthene dyes. A series of Pt-loaded SrTiO3 (Pt/STO) photocatalysts were successfully prepared to systematically investigate the dependence of photocatalytic performance on the types of sacrificial agents and dyes. Photocatalytic experiments demonstrated that triethanolamine (TEOA) sacrificial agent and Eosin Y (EY) photosensitizer were the proper choice for remarkable enhancement of photocatalytic activity, and the H2 yield of the optimal system containing 1.0 wt% Pt/STO reached 491.5 μmol in 2.5 h under visible light irradiation. The reasons causing the results were that TEOA could enhance the adsorption of xanthene dyes on SrTiO3-based photocatalysts, and bromine groups-containing EY has a high intersystem crossing yield. Electrochemical tests, PL results and fluorescence lifetime further demonstrated the efficient electron transfer behavior occurred from photoexcited EY to the conduction band of SrTiO3. This study emphasized the potential application of SrTiO3-based materials in the field of solar hydrogen production.

Preparation of Ba-doped SrTiO3 photocatalyst by sol-gel method for hydrogen generation

Increasing energy demands and its impact on the environment make it necessary to look for alternative renewable energy sources. Hydrogen is considered as energy vector but on earth, free hydrogen is not available and found in the compound state. In this study, BaxSr1-xTiO3 (x = 0.00, 0.05, 0.10 and 0.20) photocatalysts are prepared by sol-gel method for water splitting. XRD patterns showed the formation of the pure cubic structure of SrTiO3. It was observed that the optical absorption of SrTiO3 was increased by increasing Ba content. Solar to hydrogen conversion efficiency of SrTiO3 photocatalyst were increased by increasing Ba doping.

(Keynote) Large Scale Solar Hydrogen Production with Water Splitting Panel

Sunlight-driven water splitting has been studied actively for production of renewable solar hydrogen as a storable and transportable energy carrier [1]. Both the efficiency and the scalability of water-splitting systems are essential factors for practical utilization of renewable solar hydrogen because of the low areal density of solar energy. Particulate photocatalyst systems do not involve any secure electric circuit and can be spread over wide areas by inexpensive processes potentially. Therefore, it is highly impactful to develop particulate photocatalysts and their reaction systems that efficiently split water. In my talk, the latest progress in photocatalytic materials and reactors and concepts toward large-scale operation will be presented.A semiconductor photocatalyst can split water into hydrogen and oxygen thermodynamically when the band gap straddles the potentials of the hydrogen evolution reaction (0 V vs. RHE) and the oxygen evolution reaction (+1.23 V vs. RHE). SrTiO3 is a photocatalyst known to be active in overall water splitting under UV light irradiation after loading of proper cocatalysts since 1980s. The author's group has found that doping Al into SrTiO3 boosts the water splitting activity by two orders of magnitude [2]. Through tuning of the preparation and modification methods, the apparent quantum yield of photocatalytic water splitting using Al-doped SrTiO3 has reached 95% at wavelengths in the range of 350–360 nm, equivalent to an internal quantum efficiency of almost unity. This quantum efficiency is the highest yet reported, and confirms that a particulate photocatalyst can drive the greatly uphill overall water splitting reaction at a quantum efficiency comparable to values obtained from photon-to-chemical or photon-to-current conversion in photosynthesis or photovoltaic systems, respectively. Nevertheless, it is essential to develop photocatalysts active under visible light irradiation.Various oxides, (oxy)nitrides, and (oxy)chalcogenides have been investigated [3]. Ta3N5 has a band structure suitable for water splitting under visible irradiation of up to 600 nm; however, overall water splitting had not been achieved because of high densities of trap states until recently. The author’s group has developed a Ta3N5 photocatalyst active in overall water splitting via one-step excitation under visible light [4]. Ta3N5 single crystal nanorods are directly evolved on KTaO3 particles by short-time nitridation accompanied by gradual evaporation of K contents. Ta3N5 single crystal nanorods have low defect densities and can utilize photoexcited carriers in the water splitting reaction when being loaded with appropriate cocatalysts. It was also found that Y2Ti2O5S2, an oxysulfide photocatalyst, could be activated in overall water splitting by coloading cocatalysts for hydrogen evolution and oxygen evolution and finely tuning the reaction conditions [5].Two different photocatalysts can also be combined so that hydrogen and oxygen are generated on the respective photocatalysts. The author’s group has developed particulate photocatalyst sheets consisting of the hydrogen evolution photocatalyst (HEP) and the oxygen evolution photocatalyst (OEP) embedded into conductive layers by particle transfer [6,7]. A photocatalyst sheet consisting of La- and Rh-codoped SrTiO3 as a HEP and Mo-doped BiVO4 as an OEP embedded into a carbon conductor exhibits a solar-to-hydrogen energy conversion efficiency (STH) of 1.0% at ambient pressure. Some (oxy)chalcogenides and (oxy)nitrides with longer absorption edge wavelengths have also been shown to be applicable as the HEP and the OEP of particulate photocatalyst sheets recently.The author's group has been developing panel reactors that accommodate photocatalyst sheets in view of large-scale application [2]. A prototype panel reactor containing Al-doped SrTiO3 photocatalyst sheets splits water and releases product hydrogen and oxygen gas bubbles at a rate corresponding to a STH of 10% under intense UV illumination even when the water depth is merely 1 mm, and it can maintain the activity over several months under sunlight illumination [8]. A 1-m2-sized photocatalyst panel reactor splits water under natural sunlight irradiation without a significant loss of the intrinsic activity of the photocatalyst sheets. Panel reactors can accommodate various kinds of photocatalyst sheets and are expected to be built using light and inexpensive materials, being suitable for large-scale solar hydrogen production from water. A prototype solar hydrogen production system with a greater size is currently under construction.[1] Hisatomi et al. Nat. Catal. 2019, 2, 387.[2] Goto et al. Joule 2018, 2, 509.[3] Chen et al. Nat. Rev. Mater. 2017, 2, 17050.[4] Wang et al. Nat. Catal. 2018, 1, 756.[5] Wang et al. Nat. Mater. 2019, 18, 827.[6] Wang et al. Nat. Mater. 2016, 15, 611.[7] Wang et al. J. Am. Chem. Soc. 2017, 139, 1675.[8] Lyu et al. Chem. Sci., 2019, 10, 3196.

Synthesis and Photocatalytic Mechanism of the Organic Functional Groups Decorated SrTiO3 Photocatalyst

The SrTiO3 photocatalyst is successfully prepared by three different routes including a sol–gel method, a acrylamide gel method, and a hydrothermal synthesis method. Phase structure and FTIR analysis indicate that the phase purity and crystallinity of the SrTiO3 photocatalyst are strongly dependent on the synthetic route. The carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides improved the surface morphology, BET specific surface area, optical, and electrochemical properties and photocatalytic activity of the SrTiO3 photocatalyst significantly. Photocatalytic experiments indicate that the carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides exhibits highest photocatalytic activity for degradation of the congo red dye under simulated sunlight irradiation. The effects of dye concentration, catalyst concentration, and pH value on the photocatalytic activity of the carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides were systematically investigated. The excellent photocatalytic activity for the carbonate ion and C–C-stretching vibration peak decorated SrTiO3 oxides can be ascribed to the low recombination and high charge separation due to the synergistic effect of the carbonate ion and the C–C-stretching vibration peak.

Synthesis of SrTiO3 submicron cubes with simultaneous and competitive photocatalytic activity for H2O splitting and CO2 reduction.

Single crystalline strontium titanate (SrTiO3) submicron cubes have been synthesized based on a molten salt method. The submicron cubes showed superior photocatalytic activity towards both water splitting and carbon dioxide reduction, in which methane (CH4) and hydrogen (H2) were simultaneously produced. The average production rate of methane up to 8 h is 4.39 μmol g−1 h−1 but drops to 0.46 μmol g−1 h−1. However, the average production rate of hydrogen is 14.52 before 8 h but then increases to 120.23 μmol g−1 h−1 after 8 h. The rate change of the two processes confirms the competition between the H2O splitting and CO2 reduction reactions. Band structure and surface characteristics of the SrTiO3 submicron cubes were characterized by diffuse reflective UV-Vis spectroscopy, Mott–Schottky analysis, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The results reveal that the simultaneous and competitive production of methane and hydrogen is due to a thermodynamics factor, as well as the competition between the adsorption of carbon dioxide and water molecules on the surface of the faceted SrTiO3. This work demonstrates that SrTiO3 photocatalysts are efficient in producing sustainable fuels via water splitting and carbon dioxide reduction reactions.

Photocatalytic performances of heterojunction catalysts of silver phosphate modified by PANI and Cr-doped SrTiO3 for organic pollutant removal from high salinity wastewater

In this work, Ag3PO4/PANI/Cr:SrTiO3 photocatalysts were designed to effectively eliminate organic pollutants including Rhodamine B and phenol from high salinity wastewater under visible light. The phase composition, optical properties, and morphology of powders were studied, and the effects of inorganic salts on removal performance of the as-prepared particles were also tested. Results showed that the photocatalytic activities of Ag3PO4/PANI/Cr:SrTiO3 composites for Rhodamine B and phenol reached 100% within 10 min and 18 min, respectively. The reaction rate of pure Ag3PO4 was 7 times less than that of the ternary composite with the adding of PANI and Cr:SrTiO3. The activity of Ag3PO4/PANI/Cr:SrTiO3 remained at 92.25% after five cycles, so the photocatalytic and recyclable performance of ternary composite was greatly improved. In addition, when there was SO42− with a content of ranging from 1% to 21%, the degradation activity of the ternary catalyst under visible light was not changed for Rhodamine B, which indicated that the ternary catalyst exhibited the excellent sulfate resistance ability. Results from ESR and radical trapping experiments showed that O2− and h+ made an important contribution to visible-light photocatalytic activities.

The effect of imidazolium ionic liquid on the morphology of Pt nanoparticles deposited on the surface of SrTiO3 and photoactivity of Pt–SrTiO3 composite in the H2 generation reaction

Photocatalytic water splitting has great potential in solar-hydrogen production as a low-cost and environmentally friendly method. Different unique techniques used to obtain photocatalysts with various modifications to improve H2 generation have been introduced. In the present work, SrTiO3 was successfully synthesized via the solvothermal method in the presence of ionic liquid (IL) - 1-butyl-3-methylimidazolium bromide ([BMIM][Br]) followed by surface decoration with Pt particles using the photodeposition method. The effect of the noble metal content and presence of IL on the morphology, optical and surface properties of SrTiO3, thereby the effectiveness of hydrogen generation, has been thoroughly examined and presented. Unexpectedly, the presence of [BMIM][Br] at the SrTiO3 surface affected the interaction between the semiconductor surface and platinum particles formed throughout photodeposition. Platinum particles at the surface of SrTiO3_IL were found to be in the form of 2D clusters with a size of 1 nm. In comparison, Pt deposited on SrTiO3 photocatalyst without application of IL created larger, three-dimensional structures with a diameter exceeding 5 nm. This is the reason why the total amount of platinum deposited on the SrTiO3_IL sample is smaller than that on SrTiO3 and justifies a higher efficiency of hydrogen generation of Pt modified SrTiO3 photocatalyst in comparison to SrTiO3 prepared in the presence of IL. The mechanism of H2 generation in the water-splitting reaction in the presence of SrTiO3_Pt photocatalyst was discussed.

Photocatalytic Overall Water Splitting: Observing H2 and O2 Transients with Ni/NiOx-Modified Mg:SrTiO3

SrTiO3 is a promising semiconductor driving photocatalytic overall water splitting (POWS) under UV light illumination. Improving the performance of SrTiO3 in decomposing water into H2 and O2 can be achieved by introducing feasible co-catalyst, such as Pt or Ni/NiOx. Though co-catalysts are employed in heterogeneous photocatalysis engineering of semiconductor/co-catalysts interfaces is rarely reported in literature [1]. In addition, limited attention has been paid to structural/electronic changes of co-catalysts during illumination/reaction and transients occurring in hydrogen and/or oxygen evolution are barely discussed. In this contribution the photocatalytic performance of SrTiO3-based systems will be analyzed using a Continuously Stirred Tank Reactor (CSTR) connected to a micro GC-PDD (Pulsed Discharge Detector). Due to the favorable time-resolution of the GC-PDD transients in the evolution of H2 and O2, especially in the initial stages of testing, can be easily revealed. We will highlight the following recent observations: For Ni/NiOx-modified SrTiO3, severe changes in the oxidation state of NiOx assigned to the transformation of Ni(OH)2 to NiOOH leading to an active photocatalyst/co-catalyst material in agreement with transient H2 evolution will be discussed [2];Electronic modification of SrTiO3 by Mg incorporation into the perovskite structure can be obtained by a simple solid-state preparation [3]. While significant improvements in the steady state photocatalytic efficiency are obtained (Fig. 1), we also observed drastic changes in the initial transients caused by the interaction of Mg and Ni/NiOx;Finally, it will be highlighted that stabilization of the Ni/NiOx-modified Mg:SrTiO3 photocatalyst is obtained by photodeposition of CrOx from Cr(VI) containing solutions [4]. Enhanced stability is probably caused by electronic modification of Ni/NiOx as a severe influence of the back reaction of H2 and O2 was not observed for the process conditions used.Finally, the general stability of SrTiO3 in aqueous environment will be discussed. Thus, using state-of-the-art micro-GC analysis we were able to design a stable composite photocatalyst and improve the efficiency of the system (AQE) from 0.6% to >40%.

Z-scheme water splitting by microspherical Rh-doped SrTiO3 photocatalysts prepared by a spray drying method

Microspherical particles of Rh-doped SrTiO3 (SrTiO3:Rh) having size of 1–2 μm were synthesized by a spray drying (SD) method employing a water-soluble ammonium trilactatotitanate. When the calcination temperature increased up to 1200 °C, primary particles grew significantly while the microspherical morphology of the secondary particles was kept. Dynamic light scattering analysis proved well-dispersive nature of the SD sample. Photocatalytic activities of SrTiO3:Rh synthesized by the SD method, solid state reaction (SSR), and a polymerizable complex (PC) method were evaluated for H2 evolution using an electron donor such as methanol, Fe2+, or [Co(bpy)3]2+ and Z-scheme water splitting combined with BiVO4 of an O2-evolving photocatalyst and either Fe3+/2+, [Co(bpy)3]3+/2+, or reduced graphene oxide as an electron mediator. SrTiO3:Rh prepared by the SD method showed much higher activities for all Z-scheme water splitting than the samples synthesized by the SSR method. Activities of the SD sample for Z-scheme water splitting using electron shuttles, Fe3+/2+ and [Co(bpy)3]3+/2+, were slightly higher or comparable to those of the PC sample whereas the SD sample achieved higher activity in Z-scheme water splitting based on interparticle electron transfer. In addition, even when the mass of SrTiO3:Rh used for the Z-scheme system with Fe3+/2+ was decreased from 50 mg to 30 mg, the SD sample still showed high activity while the activity decreased for the SSR and PC samples. Thus, usefulness of the SD method to obtain highly active SrTiO3:Rh with well-dispersive nature has been demonstrated.