Comparison of Typical Photocatalytic Systems with Intrinsic Plasmonic Photocatalysts Based on Strontium Niobate for Water Splitting

Abstract

We report in this Review the study of conventional semiconductor‐based photocatalysts and the photocatalytic properties of SrNbO3. The history of photocatalysis, its basic principles, and the problems associated with its commercial application will be discussed. These problems can be partially alleviated by using plasmonic metal nanoparticle/semiconductor systems. Then, we will introduce a new intrinsic plasmonic photocatalyst, SrNbO3. Epitaxial films of SrNbO3 are grown as a metallic oxide by means of pulsed laser deposition. This unusual material has a band gap of 4.1 eV with a degenerate conduction band with a charge‐carrier density exceeding 1022 cm−3. This large charge‐carrier density gives rise to a plasmon that in turn causes a strong absorption in the red range of light; this was mistaken earlier by the community to arise from a mid‐gap state. When oxygen is introduced into this system, a special planar defect is formed that progressively reduces the percolation of the metallic region. Within the metallic region an unusual coherent plasmonic effect is seen, which arises from strong electronic correlation. Such a strong optical absorption enables the material to generate hydrogen from water under solar irradiation.

New Family of Plasmonic Photocatalysts without Noble Metals

“…As seen in Figure 3a, the resistivity of MNbO 3 increases when the temperature increases, showing metallic behavior. According to the density functional theory calculation, 22,24 the free carriers in MNbO 3 come from the Nb 4d states and only one electron per unit cell can be provided by the Nb 4+ ions. Thus, the theoretical maximum carrier density of CaNbO 3 , SrNbO 3 , and BaNbO 3 are 1.62 × 10 22 , 1.48 × 10 22 , and 1.41 × 10 22 cm −3 , respectively, based on the lattice constant of MNbO 3 .…”

“…With a recently discovered strong plasmonic resonance in the visible range, SrNbO 3 , a metallic oxide with a degenerate Fermi level and an extremely large carrier density (∼10 22 cm –3 ), can act as a photocatalyst . In a plasmonic system, the hot carriers are generated via Landau damping by converting the plasmon into a single electron–hole pair excitation during the decay of plasmon resonance. , Unlike the metal nanoparticle/semiconductor plasmonic system in which the carriers are generated in the metal nanoparticle and the catalysis occurs in the semiconductor only after a charge-transfer process (please see Supporting Note 1 for more detail), both carrier generation and catalysis in SrNbO 3 take place in the same systemleading to an intrinsic plasmonic photocatalyst (IPP), as illustrated in Figure a. However, the IPP material thus far is still limited to only SrNbO 3 and the methods to enhance the performance of IPP have been limited.…”

Preparation of catalyst of cobalt‐ and/or iron‐doped strontium zirconate and its performance in removal of m‐cresol using ozone as oxidant

“…5. It can be seen that all the catalysts exhibit a characteristic diffraction peak at around 31°, attributed to the SrZrO 3 (121) [25][26][27] (JCPDS#44-0161) orthorhombic crystal phase. The XRD pattern of Sr 2 Co 0.4 Fe 0.6 ZrO 6 shows some impurity peaks.…”

Low Temperature and Controllable Formation of Oxygen Vacancy SrTiO3‐x by Loading Pt for Enhanced Photocatalytic Hydrogen Evolution

“…The conversion of solar energy into H 2 via semiconductor-based photocatalytic water splitting is the most promising strategy to resolve the energy crisis and environmental pollution. [1][2][3][4][5][6][7][8][9][10][11][12] To reach this goal, it is necessary to develop highly efficient semiconductor photocatalysts. SrTiO 3 with perovskite structure is a promising photocatalyst for hydrogen evolution due to its exceptional crystal and electronic structure, photochemical stability, low cost, and high catalytic efficiency.…”

“…Hydrogen as a renewable and clean fuel has attracted extensive attention. The conversion of solar energy into H 2 via semiconductor‐based photocatalytic water splitting is the most promising strategy to resolve the energy crisis and environmental pollution . To reach this goal, it is necessary to develop highly efficient semiconductor photocatalysts.…”