ORCID Profile
0000-0002-2522-1817
Current Organisation
Dalian Institute of Chemical Physics
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Publisher: Springer Science and Business Media LLC
Date: 05-2008
Publisher: American Chemical Society (ACS)
Date: 26-03-2013
DOI: 10.1021/AR300227E
Abstract: Since the 1970s, splitting water using solar energy has been a focus of great attention as a possible means for converting solar energy to chemical energy in the form of clean and renewable hydrogen fuel. Approaches to solar water splitting include photocatalytic water splitting with homogeneous or heterogeneous photocatalysts, photoelectrochemical or photoelectrocatalytic (PEC) water splitting with a PEC cell, and electrolysis of water with photovoltaic cells coupled to electrocatalysts. Though many materials are capable of photocatalytically producing hydrogen and/or oxygen, the overall energy conversion efficiency is still low and far from practical application. This is mainly due to the fact that the three crucial steps for the water splitting reaction: solar light harvesting, charge separation and transportation, and the catalytic reduction and oxidation reactions, are not efficient enough or simultaneously. Water splitting is a thermodynamically uphill reaction, requiring transfer of multiple electrons, making it one of the most challenging reactions in chemistry. This Account describes the important roles of cocatalysts in photocatalytic and PEC water splitting reactions. For semiconductor-based photocatalytic and PEC systems, we show that loading proper cocatalysts, especially dual cocatalysts for reduction and oxidation, on semiconductors (as light harvesters) can significantly enhance the activities of photocatalytic and PEC water splitting reactions. Loading oxidation and/or reduction cocatalysts on semiconductors can facilitate oxidation and reduction reactions by providing the active sites/reaction sites while suppressing the charge recombination and reverse reactions. In a PEC water splitting system, the water oxidation and reduction reactions occur at opposite electrodes, so cocatalysts loaded on the electrode materials mainly act as active sites/reaction sites spatially separated as natural photosynthesis does. In both cases, the nature of the loaded cocatalysts and their interaction with the semiconductor through the interface/junction are important. The cocatalyst can provide trapping sites for the photogenerated charges and promote the charge separation, thus enhancing the quantum efficiency the cocatalysts could improve the photostability of the catalysts by timely consuming of the photogenerated charges, particularly the holes most importantly, the cocatalysts catalyze the reactions by lowering the activation energy. Our research shows that loading suitable dual cocatalysts on semiconductors can significantly increase the photocatalytic activities of hydrogen and oxygen evolution reactions, and even make the overall water splitting reaction possible. All of these findings suggest that dual cocatalysts are necessary for developing highly efficient photocatalysts for water splitting reactions.
Publisher: American Chemical Society (ACS)
Date: 29-10-2004
DOI: 10.1021/JP040345U
Publisher: American Chemical Society (ACS)
Date: 03-08-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9TA02735A
Abstract: Herein, we report a new class of copper complexes bearing a tetradentate polythioether ligand, [(S 4 )Cu] 2+/+ ( 1 2+/+ , S 4 = 1,4,8,11-tetrathiocyclotetradecane), as a redox mediator in dye-sensitized solar cells (DSCs).
Publisher: American Chemical Society (ACS)
Date: 17-05-2021
Publisher: Wiley
Date: 13-10-2020
Publisher: American Chemical Society (ACS)
Date: 07-01-2019
Publisher: American Chemical Society (ACS)
Date: 07-07-2010
DOI: 10.1021/JP103722J
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TA11326D
Publisher: American Chemical Society (ACS)
Date: 14-05-2020
Publisher: American Chemical Society (ACS)
Date: 02-11-2020
Publisher: Elsevier BV
Date: 05-2012
Publisher: Wiley
Date: 30-05-2014
Publisher: Elsevier BV
Date: 02-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3EE43304H
Abstract: Rational construction of dual cocatalysts corresponding to different facets with photogenerated charge separation.
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4RA07498J
Abstract: Photofuel cells have been demonstrated to be a promising strategy for generating electricity using biomass.
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5EE01398D
Abstract: Photocatalytic overall water splitting on TiO 2 -based photocatalysts is determined by both thermodynamics and kinetics simultaneously.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA00955E
Abstract: The limiting factor for low photocurrent density of polarization switchable ferroelectric BiFeO 3 film is due to severe charge recombination at the interfaces of the domain walls rather than recombination inside the domains.
Publisher: American Chemical Society (ACS)
Date: 17-06-2019
Publisher: Oxford University Press (OUP)
Date: 20-04-2015
DOI: 10.1093/NSR/NWV016
Publisher: American Chemical Society (ACS)
Date: 06-2005
DOI: 10.1021/JA052002V
Abstract: Hydrocarbon diradical 1, a new stable, 3-fold symmetric analogue of trimethylenemethane (TMM) with no heteroatom perturbation, is prepared and studied. Such diradicals should provide new building blocks for high-spin hydrocarbon polyradicals with very strong net ferromagnetic coupling. Magnetic studies (SQUID) and EPR spectroscopy indicate that 1 in tetrahydrofuran-d8 (THF-d8) possesses a triplet (S = 1) ground state, with strong ferromagnetic coupling. After annealing at room temperature, the EPR spectra of 1 (approximately 0.02 M in frozen THF-d8) consist of a single narrow resonance (deltaH(pp) < 1 G), and intermolecular antiferromagnetic coupling is increased by 1 order of magnitude. This behavior is consistent with the presence of exchange narrowing, thus suggesting aggregation of 1 in THF-d8. Blue solutions of 1 in THF-d8 possess a strong UV-vis absorption band at lambda(max) approximately 640 nm. Diradical 1 in THF-d8 is stable (or persistent) at room temperature, with no detectable decomposition for at least 2 days.
Publisher: Elsevier BV
Date: 09-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3CC46515B
Abstract: Glycerol is selectively converted to hydroxyacetaldehyde (HAA) and H2 in aqueous solution on TiO2-based photocatalysts. The product selectivity was verified to be strongly dependent on the facets of TiO2. Rutile with high percentage of {110} facets results in over 90% superior selectivity of HAA, while anatase with {001} or {101} facets gives only 16% and 49% selectivity for HAA, respectively.
Publisher: Elsevier BV
Date: 11-2013
Publisher: Wiley
Date: 21-11-2018
Abstract: Fundamentals of water electrolysis, and recent research progress and trends in the development of earth-abundant first-row transition-metal (Mn, Fe, Co, Ni, Cu)-based oxygen evolution reaction (OER) and hydrogen evolution (HER) electrocatalysts working in acidic, alkaline, or neutral conditions are reviewed. The HER catalysts include mainly metal chalcogenides, metal phosphides, metal nitrides, and metal carbides. As for the OER catalysts, the basic principles of the OER catalysts in alkaline, acidic, and neutral media are introduced, followed by the review and discussion of the Ni, Co, Fe, Mn, and perovskite-type OER catalysts developed so far. The different design principles of the OER catalysts in photoelectrocatalysis and photocatalysis systems are also presented. Finally, the future research directions of electrocatalysts for water splitting, and coupling of photovoltaic (PV) panel with a water electrolyzer, so called PV-E, are given as perspectives.
Publisher: Springer Science and Business Media LLC
Date: 05-02-2013
DOI: 10.1038/NCOMMS2401
Abstract: Charge separation is crucial for increasing the activity of semiconductor-based photocatalysts, especially in water splitting reactions. Here we show, using monoclinic bismuth vanadate crystal as a model photocatalyst, that efficient charge separation can be achieved on different crystal facets, as evidenced by the reduction reaction with photogenerated electrons and oxidation reaction with photogenerated holes, which take place separately on the {010} and {110} facets under photo-irradiation. Based on this finding, the reduction and oxidation cocatalysts are selectively deposited on the {010} and {110} facets respectively, resulting in much higher activity in both photocatalytic and photoelectrocatalytic water oxidation reactions, compared with the photocatalyst with randomly distributed cocatalysts. These results show that the photogenrated electrons and holes can be separated between the different facets of semiconductor crystals. This finding may be useful in semiconductor physics and chemistry to construct highly efficient solar energy conversion systems.
Publisher: American Chemical Society (ACS)
Date: 28-06-2017
Abstract: The influence of the electrostatic interaction on photocatalytic H
Publisher: Elsevier BV
Date: 08-2011
Publisher: American Chemical Society (ACS)
Date: 26-08-2020
Publisher: Wiley
Date: 30-05-2014
Abstract: Photoelectrochemical (PEC) water splitting is an ideal approach for renewable solar fuel production. One of the major problems is that narrow bandgap semiconductors, such as tantalum nitride, though possessing desirable band alignment for water splitting, suffer from poor photostability for water oxidation. For the first time it is shown that the presence of a ferrihydrite layer permits sustainable water oxidation at the tantalum nitride photoanode for at least 6 h with a benchmark photocurrent over 5 mA cm(-2) , whereas the bare photoanode rapidly degrades within minutes. The remarkably enhanced photostability stems from the ferrihydrite, which acts as a hole-storage layer. Furthermore, this work demonstrates that it can be a general strategy for protecting narrow bandgap semiconductors against photocorrosion in solar water splitting.
Publisher: Elsevier BV
Date: 06-2007
Publisher: Wiley
Date: 19-11-2012
Abstract: When Alpha met Beta: a tuneable α-β surface phase junction on Ga(2)O(3) can significantly improve photocatalytic overall water splitting into H(2) and O(2) over in idual α-Ga(2)O(3) or β-Ga(2)O(3) surface phases. This enhanced photocatalytic performance is mainly attributed to the efficient charge separation and transfer across the α-β phase junction.
Publisher: American Chemical Society (ACS)
Date: 03-05-2008
DOI: 10.1021/JP800556G
Publisher: Elsevier BV
Date: 11-2010
Publisher: American Chemical Society (ACS)
Date: 15-06-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C5RA18307C
Abstract: Enhanced photoresponsivity of the R-NRA device is due to the enhancement of charge separation and transfer at the electrode/electrolyte interface.
Publisher: American Chemical Society (ACS)
Date: 02-01-2020
Publisher: American Chemical Society (ACS)
Date: 07-08-2014
DOI: 10.1021/CR500008U
Publisher: American Chemical Society (ACS)
Date: 02-12-2020
Publisher: Elsevier BV
Date: 05-2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6SC01611A
Abstract: The key to phase junctions for efficient charge separation is to consider both the phase alignment and interface structure.
Publisher: Wiley
Date: 04-12-2012
Publisher: Wiley
Date: 05-12-2019
Publisher: Elsevier BV
Date: 12-2015
Publisher: American Chemical Society (ACS)
Date: 26-02-2016
Publisher: Wiley
Date: 19-11-2012
Publisher: Springer Science and Business Media LLC
Date: 14-02-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2CP41153A
Abstract: The surface features of semiconductors play very important roles in photocatalytic processes but they are far from being well understood. In this work, we used CdS nanocrystals (NCs) as a model semiconductor photocatalyst to investigate the influence of surface features on photocatalytic activity. The effects of surface modification on the recombination behavior were studied by photoluminescence (PL) spectroscopy. The surface of CdS NCs was modified by tuning the surface S/Cd ratio or by co-loading with Pt and/or PdS co-catalysts. It was found that the surface modifications significantly affect the emission bands at ~540 nm due to shallow traps and ~650 nm assigned to S(2-) vacancies, and consequently the photocatalytic activities. Without co-catalysts loading, the excited carriers are readily transferred to the shallow traps, while they are readily transferred to the co-catalysts upon co-catalysts loading. These results demonstrate that the surface features are crucial to photocatalytic activity of the CdS NCs. The surface modification is helpful for the excited carriers to transfer to either the shallow trap states or co-catalysts, resulting in higher quantum efficiency of photocatalytic H(2) production.
Publisher: American Chemical Society (ACS)
Date: 06-09-2013
DOI: 10.1021/JA408376T
Abstract: A [FeFe]-hydrogenase model (1) containing a chelating diphosphine ligand with a pendant amine was readily oxidized by Fc(+) (Fc = Cp2Fe) to a Fe(II)Fe(I) complex ([1](+)), which was isolated at room temperature. The structure of [1](+) with a semibridging CO and a vacant apical site was determined by X-ray crystallography. Complex [1](+) catalytically activates H2 at 1 atm at 25 °C in the presence of excess Fc(+) and P(o-tol)3. More interestingly, the catalytic activity of [1](+) for H2 oxidation remains unchanged in the presence of ca. 2% CO. A computational study of the reaction mechanism showed that the most favorable activation free energy involves a rotation of the bridging CO to an apical position followed by activation of H2 with the help of the internal amine to give a bridging hydride intermediate.
Publisher: Elsevier BV
Date: 07-2014
Publisher: American Chemical Society (ACS)
Date: 19-09-2008
DOI: 10.1021/JP803994D
Publisher: American Chemical Society (ACS)
Date: 02-03-2020
Publisher: American Chemical Society (ACS)
Date: 13-12-2021
Publisher: Royal Society of Chemistry (RSC)
Date: 08-07-2014
DOI: 10.1039/C4CP02567A
Abstract: Introducing appropriate dual cocatalysts is one of the most efficient strategies to improve the photocatalytic activity. Herein, we investigated the promotion effect of dual cocatalysts on TiO2 for hydrogen production. Compared with the Pd/TiO2 and Ir/TiO2 with the in idual cocatalyst, TiO2 coloaded with Pd and Ir species exhibited an obviously enhanced H2 production activity and reduced CO/H2 ratio. XPS and IR spectra of CO adsorption analysis indicated that the dual cocatalysts on TiO2 were actually composed of Pd(0) and partially oxidized IrOx, which acted as the reduction and oxidation cocatalysts, respectively. Interestingly, EDX elemental mappings of Pd and Ir indicated that the two elements on TiO2 were inclined to depositing together. The synergetic effect of reduction and oxidation cocatalysts with their intimate contact is proposed to contribute to the high H2 production activity, which is different from the common view that the reduction and oxidation sites should be spatially separated to avoid the charge recombination.
Publisher: Springer Science and Business Media LLC
Date: 15-09-2020
DOI: 10.1038/S41467-020-18484-8
Abstract: Hematite has a great potential as a photoanode for photoelectrochemical (PEC) water splitting by converting solar energy into hydrogen fuels, but the solar-to-hydrogen conversion efficiency of state-of-the-art hematite photoelectrodes are still far below the values required for practical hydrogen production. Here, we report a core-shell formation of gradient tantalum-doped hematite homojunction nanorods by combination of hydrothermal regrowth strategy and hybrid microwave annealing, which enhances the photocurrent density and reduces the turn-on voltage simultaneously. The unusual bi-functional effects originate from the passivation of the surface states and intrinsic built-in electric field by the homojunction formation. The additional driving force provided by the field can effectively suppress charge–carrier recombination both in the bulk and on the surface of hematite, especially at lower potentials. Moreover, the synthesized homojunction shows a remarkable synergy with NiFe(OH) x cocatalyst with significant additional improvements of photocurrent density and cathodic shift of turn-on voltage. The work has nicely demonstrated multiple collaborative strategies of gradient doping, homojunction formation, and cocatalyst modification, and the concept could shed light on designing and constructing the efficient nanostructures of semiconductor photoelectrodes in the field of solar energy conversion.
Publisher: American Chemical Society (ACS)
Date: 10-01-2022
Publisher: American Chemical Society (ACS)
Date: 26-10-2020
No related grants have been discovered for Hongxian Han.