Selenium-Rich Configuration and Amorphization for Synergistically Maximizing the Active-Center Amount of CoSe_1+x Nanodots toward Efficient Photocatalytic H₂ Evolution

Abstract

Transition-metal selenides have been evidenced to be promising candidates for efficient H 2 evolution cocatalysts due to a similar Se−H ads (273 kJ/ mol) bond energy to Pt−H (251 kJ/mol), while their H 2 evolution activity is still limited by the insufficient exposure of active Se atoms. Herein, a synergic idea of selenium-rich configuration and amorphization was developed to construct selenium-rich amorphous CoSe 1+x nanodots for maximum exposure of more hydrogen-production selenium sites. For this purpose, the selenium-rich amorphous CoSe 1+x nanodots with an ultrasmall size (0.2−1 nm) and seleniumrich character can be resourcefully and uniformly grafted with a TiO 2 photocatalyst via the facile photoinduced electron-reduction way. Photocatalytic results showed that the as-prepared selenium-rich a-CoSe 1+x /TiO 2 (0.5 wt %) attains a maximal hydrogen production activity (3400 μmol h −1 g −1 , AQE = 16.3%), which is significantly superior to those of crystalline c-CoSe/TiO 2 and conventional amorphous a-CoSe/TiO 2 samples by a factor of 3.2 and 1.6 times, respectively. The outstanding activity can be ascribed to the cooperation of accelerated photoinduced electron migration from TiO 2 to a-CoSe 1+x and rapid hydrogen evolution on the enriched active Se sites. Meaningfully, the selenium-rich a-CoSe 1+x can also be employed as the general H 2 evolution electron cocatalyst for CdS and g-C 3 N 4 photocatalysts. This work sheds light on the ingenious design and construction of efficient and inexpensive active-site-rich cocatalysts for highly active photocatalytic materials.

Simultaneously Optimizing the Number and Efficiency of Active Se Sites in Se‐Rich a‐MoSex Nanodot Cocatalysts for Efficient Photocatalytic H2 Evolution

“…As elucidated in Figure 11A, after the modification of Se-rich amorphous MoSe x nanodots, the resultant a-MoSe x / TiO 2 sample achieves an increased average lifetime compared with the blank TiO 2 , which means a suppressed recombination of photogenerated charges. [59,60] Their corresponding steadystate PL spectra (Figure S3, Supporting Information) supports that a remarkable fluorescence quenching can be observed on the a-MoSe x /TiO 2 photocatalyst, strongly corroborating a reduced photoinduced electron-hole recombination by modifying the Se-rich amorphous MoSe x nanodots. Furthermore, the smallest arc radius of Nyquist plot can be identified in the a-MoSe x /TiO 2 photocatalyst (Figure 11B), indicating an efficient charge transfer for the charge separation.…”

A one-step solvothermal synthesis of the topological insulator Bi2Te3 nanorod-modified TiO2 photocatalyst for enhanced H2-evolution activity

“…5A-a) shows the adventitious C 1s, Ti 2p and O 1s element signals. 40 After modification by Bi 2 Te 3 , new Bi 4f and Te 3d signals appear in the Bi 2 Te 3 /TiO 2 samples (Fig. 5A-b and c) apart from the above elements.…”

“…Therefore, in situ XPS results can well verify the migration of photoinduced electrons from TiO 2 to Bi 2 Te 3 which efficiently promotes the photoinduced charge separation. 40,45 Once the photoinduced electrons are transferred to the Bi 2 Te 3 surface, the structure of topological insulator Bi 2 Te 3 nanorods should be investigated and the structure model of the front, top and side views Bi 2 Te 3 on the (110) face is presented in Fig. 9A-a-c, respectively.…”

Increasing unsaturated Se number and facilitating atomic hydrogen adsorption of WSe2+x nanodots for improving photocatalytic H2 production of TiO2

“…[1][2][3][4][5] Unfortunately, most photocatalysts usually suffer from the rapid quenching of photogenerated carriers and depressed interfacial H 2 -generation dynamics. [6][7][8][9][10] To overcome the above shortcomings, a variety of tactics have been developed, including defect engineering, 11 construction of heterojunctions, 12,13 loading cocatalysts, etc. [14][15][16] Among them, loading cocatalysts has been recognized to be a simple and effective strategy for boosting photocatalytic H 2 -evolution activity by enhancing photocarrier separation and providing available catalytically active sites.…”