尽管S型人工光合系统在驱动光催化制氢方面具有潜力，但传统方法往往过于关注单个还原位点。这些体系的氧化还原能力和电荷分离能力较差，影响了光催化析氢反应。为了克服这一限制，我们提出了一种设计双S型系统的新策略，该系统利用双还原位，从而保留高能光电子和空穴，以提高表观量子效率。在这项工作中，作者提出了一种双S型结，由锐钛矿型TiO2纳米粒子修饰的CdS纳米球与石墨氮化碳偶联而成。在365 nm波长处，催化剂的析氢速率为26.84 mmol g−1h−1，表观量子效率高达40.2%。这种光催化析氢性能的增强归因于双S型诱导的高效分离和传输。为了支持这一点，理论计算和综合光谱测试(原位和非原位)都证实了催化剂界面上有效的电荷传输。此外，用类似的硫化物如ZnIn2S4、ZnS、MoS2和In2S3代替还原型催化剂CdS进一步证实了所提出的双S型构型的可行性。研究发现为设计更有效的双S型人工光合系统提供了一条途径，为提高光催化析氢性能开辟了新的视角。
Figure 1. Schematic diagram of heterojunction design and double S-scheme artificial photosynthetic system.
Figure 2. (a) TEM and (b) HAADF-STEM images of the DRSP heterojunction. (c) Schematic illustration of DRSP junction composed of CdS nanospheres (orange), anatase titanium dioxide nanoparticles (green) and graphitic carbon nitride nanosheets (yellow). (d,e) Enlarged images respectively of the brown and blue rectangles (f,g) FFT images obtained from the corresponding red square (CdS nanosphere) and yellow square (anatase TiO2 nanoparticles), respectively. (h) STEM elemental mapping of DRSP. (i) XRD patterns of pristine g-C3N4, CdS, a-TiO2, CdTi and DRSP. (j) Zeta potential of pristine CdS, a-TiO2 and g-C3N4, respectively.
Figure 3. In situ and ex situ X-ray photoelectron spectroscopy spectra of (a) Cd 3d, (b) C 1s, (c) Ti 2p. The electrostatic potentials and corresponding models of (d, g) CdS, (e, h) g-C3N4 and (f, i) a-TiO2. The light pink, yellow, grey, blue, silver, and red spheres represent Cd, S, C, N, Ti and O atoms, respectively. Purple and red dashed lines indicate the vacuum and Fermi energy levels.
Figure 4. Electron spin-resonance spectroscopy (ESR) signals of CdS, a-TiO2, g-C3N4, CdTi and DRSP (a) in methanol dispersion for DMPO-superoxide radical and (b) in aqueous dispersion for DMPO-hydroxyl radical under UV-vis light for 5 min, respectively. In situ ESRspectra of DRSP (c) in methanol dispersion and (d) aqueous dispersion under dark condition (purple line) and 5, 10, 15, 30 min of light irradiation, respectively. e) UV-visible DRS of CdS, a-TiO2, g-C3N4 and DRSP. f) Corresponding Tauc plots for CdS, a-TiO2, g-C3N4 and DRSP using (F(R)hv)1/2 (Kubelka-Munk parameter) as a function of the photon energy. g) VB-XPS spectra of CdS, a-TiO2 and g-C3N4. h) Band alignments for dual reduction site induced by double S-scheme heterojunction.
Figure 5. Transient absorption spectra of a,b) CdS, d,e) a-TiO2, g,h) g-C3N4, and j,k) DRSP catalyst. Normalized transient absorption kinetics for c) CdS, f) a-TiO2, i) g-C3N4, and l) DRSP catalyst after 400 nm laser excitation.
Figure 6. a) Photocatalytic H2 evolution rate of the DRSP compared with CdS, g-C3N4, a-TiO2 and CdTi under UV-visible irradiation (wavelength range: 200-1000 nm). Photocatalytic H2 evolution rate of different mass ratio of b) binary CdTi-X catalysts, c) DRSP-X, d) different loading amount of Pt on DRSP-3 and e) DRSP replaced by different reduction-type semiconductors. f) Cycling experiments of DRSP under UV-visible light. g) Photocatlaytic H2 evolution rates achieved by DRSP as compared other catalysts previously reported in the literature.
Artificial Photosynthetic System with Spatial Dual Reduction Site Enabling Enhanced Solar Hydrogen Production
https://doi.org/10.1002/adma.202309199