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TiO2-based photocatalysts are eco-friendly, cost-effective, and stable but only exert catalytic performance in the ultraviolet region, and the photocatalytic efficiency is very low. In this work, we employ DFT calculations to deeply investigate the effect of nonmetallic C-doped TiO2 (101) on the photocatalytic hydrogen evolution performance. Specifically, the effects of C substitution or interstitial doping at the surface, subsurface, and bulk on the electronic structure, optical properties, and catalytic hydrogen evolution activity were substantially investigated. We discovered that different C atom doping strategies impinge different effects on the catalytic activity. Among them, the CO-bulk4, CTi-surf2, and Cinter-surf systems showed superior catalytic activities with ΔG of −0.012, −0.055, and −0.024 eV, respectively. The C atom replaces the Ti atom and alters the original coordination environment, which leads to charge redistribution and consequently to the activation of the O sites. Additionally, carbon-self-doped TiO2 photocatalysts were fabricated using an experimental hydrothermal synthesis, and the XPS analyses confirmed that O is replaced by C. In addition, the photocatalytic hydrogen evolution rate is 0.3 mmol g–1 h–1, while there is no hydrogen evolution for pure TiO2. Our findings suggest that nonmetallic doped TiO2(101) photocatalysts can improve light absorption, modulate charge distribution, and enhance hydrogen evolution activity. [ABSTRACT FROM AUTHOR]

The development of high-activity photocatalysts is crucial for the current large-scale development of photocatalytic hydrogen applications. Herein, we have developed a strategy to significantly enhance the hydrogen photocatalytic activity of Cu/Pr di-atom co-modified TiO 2 architectures by selectively anchoring Cu single atoms on the oxygen vacancies of the TiO 2 surface and replacing a trace of Ti atoms in the bulk with rare earth Pr atoms. Calculation results demonstrated that the synergistic effect between Cu single atoms and Pr atoms regulates the electronic structure of Cu/Pr-TiO 2 , thus promoting the separation of photogenerated carriers and their directional migration to Cu single atoms for the photocatalytic reaction. Furthermore, the d-band center of Cu/Pr-TiO 2 , which is located at -4.70 eV, optimizes the adsorption and desorption behavior of H*. Compared to TiO 2 , Pr-TiO 2 , and Cu/TiO 2 , Cu/Pr-TiO 2 displays the best H* adsorption Gibbs free energy (-0.047 eV). Furthermore, experimental results confirmed that the photogenerated carrier lifetime of Cu/Pr-TiO 2 is not only the longest (2.45 ns), but its hydrogen production rate (34.90 mmol g -1 h -1 ) also significantly surpasses those of Cu/TiO 2 (13.39 mmol g -1 h -1 ) and Pr-TiO 2 (0.89 mmol g -1 h -1 ). These findings open up a novel atomic perspective for the development of optimal hydrogen activity in dual-atom-modified TiO 2 photocatalysts.

Photocatalytic water splitting for clean hydrogen production has been a very attractive research field for decades. However, the insightful understanding of the actual active sites and their impact on catalytic performance is still ambiguous. Herein, a Pr-doped TiO 2 -supported Cu single atom (SA) photocatalyst is successfully synthesized (noted as Cu/Pr-TiO 2 ). It is found that Pr dopants passivate the formation of oxygen vacancies, promoting the density of photogenerated electrons on the CuSAs, and optimizing the electronic structure and H * adsorption behavior on the CuSA active sites. The photocatalytic hydrogen evolution rate of the obtained Cu/Pr-TiO 2 catalyst reaches 32.88 mmol g -1  h -1 , 2.3 times higher than the Cu/TiO 2 . Innovatively, the excellent catalytic activity and performance is attributed to the active sites change from O atoms to CuSAs after Pr doping is found. This work provides new insight for understanding the accurate roles of single atoms in photocatalytic water splitting., (© 2024 Wiley‐VCH GmbH.)

Potassium-ion batteries (PIBs) have attracted much attention due to their low production cost and abundant resources. Germanium is a promising alloying-type anode with a high theoretical capacity for PIBs, yet suffering significant volume expansion and sluggish potassium-ion transport kinetics. Herein, a rational strategy is formulated to disperse Ge atoms into transition metal V-S sulfide frameworks to form a loosely packed and metallic GeV 4 S 8 medium. The theoretical prediction shows that GeV 4 S 8 is conducive to the adsorption and diffusion of K + . The V-S frameworks provide fast ion/electron diffusion channels and also help to buffer the volume expansion during K + insertion. In situ and ex situ characterizations manifest that KGe alloy clusters are constrained and dispersed by potassiated VS 2 topological structure during discharging, and revert to the original GeV 4 S 8 after charging. Consequently, as a novel anode for PIBs, GeV 4 S 8 provides a high specific capacity of ≈400 mAh g -1 at 0.5 C, maintaining 160 mAh g -1 even at 12.5 C and ≈80% capacity after 1000 cycles at 5 C, superior to most of the state-of-the-art anode materials. The proposed strategy of combining alloy and intercalation dual-functional units is expected to open up a new way for high-capacity and high-rate anode for PIBs., (© 2024 Wiley‐VCH GmbH.)