Solar-to-Chemical Conversion. Группа авторов

3.7 Photosystem II from T. vulcanus (PDB ID: 3WU2, a) and major redox‐active components within a PS‐II monomer involved in the main‐pathway electron transfer indicated with red arrows (b).Figure 3.8 The cycle of intermediate oxidation states of the oxygen‐evolving complex. Water is assumed to bind at the S₃ state of the cluster and upon reconstitution of the S₀ state. The S₄ state is a postulated but unobserved transient intermediate that decays spontaneously to S₀ with release of dioxygen.Figure 3.9 The Mn₄CaO₅ cluster and its protein pocket in the dark‐stable S₁ state as revealed by protein crystallography (PDB ID: 3WU2, a), and a scheme showing the commonly used labeling of the ions comprising the inorganic core.Figure 3.10 Proposed models for the inorganic core in the S₂ state of the OEC, with the first coordination sphere mostly omitted for clarity. The different magnetic topologies of the two valence isomers, as expressed through the pairwise exchange coupling constants J_ij (values shown in cm⁻¹; J < 0 is antiferromagnetic coupling), lead to different total spin states and g values for the corresponding EPR signals.Figure 3.11 The S₂ → S₃ transition according to Retegan et al. [191] and possible isovalent Mn(IV)₄ components of the S₃ state; the superscript “W” indicates binding of an additional water ligand.Figure 3.12 Two selected scenarios for the nature of the S₄ state and OO bond formation from the computational literature: (a) formation of a Mn1(IV)‐oxyl group in the S₄ state is followed by odd‐electron radical oxyl–oxo coupling [285], and (b) formation of a five‐coordinate high‐spin Mn4(V)‐oxo is followed by intramolecular nucleophilic coupling with concerted water binding [289]. Thick lines indicate direction of Jahn–Teller axes of Mn(III) ions.Figure 3.13 Reaction mechanism of RuBisCO proposed by Taylor and Andersson. Source: Taylor and Andersson [351].

      3 Chapter 4Figure 4.1 Schematic illustration of photocatalytic hydrogen generation over a semiconductor photocatalyst [8].Figure 4.2 Band levels of various semiconductor photocatalysts. Source: Lu et al. [15].Figure 4.3 Schematic cells for rutile phase (a) and anatase phase (b) of TiO₂. Source: Thompson and Yates [16].Figure 4.4 Photocatalytic H₂ evolution of pure TiO₂, Degussa P25, and TiO₂ with different amounts of Zn. Source: Al‐Mayman et al. [25].Figure 4.5 Hydrogen evolution on the bare and metallic TiO₂ photocatalysts using the benchmark Degussa P25 TiO₂ and its bimetallic materials as the references. Source: Wang et al. [26].Figure 4.6 Photocatalytic hydrogen evolution on TiO₂‐supported Au–Pd nanoparticles using a range of alcohols. Source: Su et al. [27].Figure 4.7 Schematic representation of the band structure of pure and N‐doped anatase TiO₂. Note that the energies are not in scale. Source: Di Valentin et al. [32].Figure 4.8 The photocatalyst H₂ generation rate of 2.5 wt%‐Cu₂O/TiO₂ with different sacrificial reagents. Source: Li et al. [34].Figure 4.9 (a) The energy band structure of ZnO/ZnS heterojunction. (b) The graphic structure of ZnO‐dotted ZnS. Source: Wu et al. [37].Figure 4.10 Tri‐s‐triazine‐based structure of g‐C₃N₄. The C and N atoms are indicated by gray and blue balls [8].Figure 4.11 Photocatalytic H₂ production over the bulk C₃N₄, C₃N₄ NSs, and C₃N₄ NTs under visible‐light irradiation. Source: Zhu et al. [54].Figure 4.12 Graphic design of preparation of cobalt‐doped g‐C₃N₄. Source: Chen et al. [57].Figure 4.13 (a) EIS, (b) photocurrent response, and steady‐state (c) and transient (d) PL spectra of g‐C₃N4 and B‐doped g‐C₃N₄ samples. Source: Chen et al. [60].Figure 4.14 Schematic illustration of the charge transfer for the three types of heterojunctions [8].Figure 4.15 Graphic illustration of the proposed mechanism for cobalt oxide/C₃N₄ NT heterojunction for photocatalytic H₂ evolution. Source: Zhu et al. [61].Figure 4.16 Schematic diagram of the photocatalytic mechanism in WO₃/MCN. Source: Kailasam et al. [63].Figure 4.17 The average H₂ evolution rate of the SiC nanowires and modified SiC nanowires. Source: Hao et al. [66].Figure 4.18 Illustration of lanthanide upconversion nanoparticles (UCNPs).Figure 4.19 Illustrative diagrams of energy transfer among NYFG(15)/C₃N₄ NTs. Source: Zhu et al. [67].Figure 4.20 The proposed mechanism of the improved photocatalytic activity in the N‐CDs/CdS photocatalyst. Source: Shi et al. [69].Figure 4.21 Graphic diagram of the FeS₂–TiO₂ heterostructures under ultraviolet, visible, and NIR light irradiation for photocatalytic H₂ evolution. Source: Kuo et al. [71].Figure 4.22 (a) The UV–vis near‐infrared absorption spectrum. (b) Photocatalytic hydrogen evolution for amorphous TiO₂–x. Source: Jiang et al. [74]Figure 4.23 Methanol and its dissociative species underwent two‐electron oxidation in photocatalytic H₂ production process over Au–Pt alloyed TiO₂ nanocomposites. Source: Al‐Mayman et al. [25].

      4 Chapter 5Figure 5.1 The schematic illustration of the features of H₂ production by PV + EC, PEC, and PC in the five aspects of cost, STH efficiency, technology readiness, H₂/O₂ separation, and catalyst stability.Figure 5.2 The schematic illustration of three steps in PEC water splitting process. Source: From Wang and Wang [7]. © 2018 Elsevier.Figure 5.3 The illustration of semiconductor–electrolyte interface and the corresponding band bending. (a, b) The scheme and energy level of semiconductor and electrolyte in vacuum. The electrons are uniformly distributed around the core of atoms (blue dot). (c, d) The schematic illustration of electron distribution and the energy band bending when SEI is built. The electrons (red dot) are accumulated at the SEI interface. (e, f) The schematic illustration of electron–hole separation and transfer under illumination.Figure 5.4 (a) The oxygen vacancy concentration change by adjusting the treatment duration in N₂. (b) The volcano relationship between photocurrent and oxygen vacancy concentration. Source: Wang et al. [39]. © 2019 Willey.Figure 5.5 (a) The schematic charge transfer in particulate Ta₃N₅ photoanode. (b) The change of charge separation and transfer efficiency for Ta₃N₅ photoanode when the charge transfer and generation are improved gradually. Source: Wang et al. [45]. Licensed under CC BY 3.0 Unported.Figure 5.6 (a) The image and (b) the photoresponse (red curve) of branched 2D porous TiO₂ single‐crystal nanosheet photoelectrode. Insert (a) illustrates the photocharge transfer during PEC process. Source: Butburee et al. [71]. Reproduced with the permission from Wiley.Figure 5.7 (a) The surface state distribution characterization by cyclic voltammetry (CV) and the surface state related capacitance (C_ss). The different hematite photoelectrodes are compared including Ti doping, Al₂O₃ passivation, and H₂O₂ treatment. (b) The schematic illustration of PEC reaction via the surface states as intermediates. Source: From Wang et al. [8]. © 2016 Royal Society of Chemistry.Figure 5.8 The schematic illustration of cocatalyst design strategy based on a charge storage layer between the semiconductor and the effective cocatalyst layer.Figure 5.9 The schematic illustration of three different types of unbiased PEC water splitting systems. PA, PC, and PV represent photoanode, photocathode, and photovoltaic, respectively. The j–E curves represent their photoresponses in a three‐electrode system. The intersections (red dots) indicate the unbiased operation points.

      5 Chapter 6Figure 6.1 Schematic illustration of photocatalytic oxygen evolution systems: (a) homogeneous and (b) heterogeneous configuration.Figure 6.2 Structures of (a) PS‐II‐OEC natural WOCs and (b) λ‐MnO₂, (c) Mn₄O₄L₆ core, and (d) Co₄O₄(Ac)₄(py)₄ artificial WOCs. Source: From McCool et al. [27]. © 2011 American Chemical Society.Figure 6.3 Ball‐and‐stick model of (a) Mn₄POM core, (b) polyhedral Mn₄POM, and (c) S₀ state of the natural OEC model. (d) Cycle diagram for the electron transfer within the S₀ → S₄ Kok cycle of the natural PS‐II‐OEC. (e) Photocatalytic oxygen evolution of Mn₄POM within the [Ru(bpy)₃]²⁺/Na₂S₂O₈