Yucheng Hu

Bio: Yucheng Hu is an academic researcher from Xihua University. The author has contributed to research in topics: Materials science & Medicine. The author has an hindex of 1, co-authored 4 publications receiving 5 citations.

Dispersion Effects in Stabilizing Organometallic Compounds: Tetra-1-norbornyl Derivatives of the First-Row Transition Metals as Exceptional Examples.

Abstract: In 1972 Bower and Tennett first synthesized a series of tetra-1-norbornyl derivatives, (nor)4M, of the first-row transition metals from titanium to cobalt. These were found to be exceptionally stab...

Research on the Influence of the Interfacial Properties Between a Cu3BiS3 Film and an In x Cd1− x S Buffer Layer for Photoelectrochemical Water Splitting

Abstract: The ternary compound photovoltaic semiconductor Cu3BiS3 thin film‐based photoelectrode demonstrates a quite promising potential for photoelectrochemical hydrogen evolution. The presented high onset potential of 0.9 VRHE attracts much attention and shows that the Cu3BiS3 thin films are quite good as an efficient solar water splitting photoelectrode. However, the CdS buffer does not fit the Cu3BiS3 thin film: the conduction band offset between CdS and Cu3BiS3 reaches 0.7 eV, and such a high conduction band offset (CBO) significantly increases the interfacial recombination ratio and is the main reason for the relatively low photocurrent of the Cu3BiS3/CdS photoelectrode. In this study, the InxCd1−xS buffer layer is found to be significantly lowered the CBO of CBS/buffer and that the In incorporation ratio of the buffer influences the CBO value of the CBS/buffer. The Pt‐TiO2/In0.6Cd0.4S/Cu3BiS3 photocathode exhibits an appreciable photocurrent density of ≈12.20 mA cm−2 at 0 VRHE with onset potential of more than 0.9 VRHE, and the ABPE of the Cu3BiS3‐based photocathode reaches the highest value of 3.13%. By application of the In0.6Cd0.4S buffer, the Cu3BiS3‐BiVO4 tandem cell presents a stable and excellent unbiased STH of 2.57% for over 100 h.

Process Accumulated 8% Efficient Cu2ZnSnS4‐BiVO4 Tandem Cell for Solar Hydrogen Evolution with the Dynamic Balance of Solar Energy Storage and Conversion

Abstract: A process accumulated record solar to hydrogen (STH) conversion efficiency of 8% is achieved on the Cu2ZnSnS4‐BiVO4 tandem cell by the synergistic coupling effect of solar thermal and photoelectrochemical (PEC) water splitting with the dynamic balance of solar energy storage and conversion of the greenhouse system. This is the first report of a Cu2ZnSnS4‐BiVO4 tandem cell with a high unbiased STH efficiency of over 8% for solar water splitting due to the greenhouse device system. The greenhouse acts as a solar thermal energy storage cell, which absorbs infrared solar light and storage as thermal energy with the solar light illumination time, while thermoelectric device (TD) converts thermal energy into electric power, electric power is also recycled and added onto Cu2ZnSnS4‐BiVO4 tandem cell for enhanced overall water splitting. Finally, the solar water splitting properties of the TD‐Cu2ZnSnS4‐BiVO4 integrated tandem cell in pure natural seawater are demonstrated, and a champion STH efficiency of 2.46% is presented, while a large area (25 cm2) TD‐Cu2ZnSnS4‐BiVO4 integrated tandem device with superior long‐term stability is investigated for 1 week, which provides new insight into photoelectrochemical solar water splitting devices.

Comparative Study of the Thermal Stabilities of the Experimentally Known High-Valent Fe(IV) Compounds Fe(1-norbornyl) 4 and Fe(cyclohexyl) 4

Abstract: The high stability of the experimentally known homoleptic 1-norbornyl derivative (nor)4Fe of iron in the unusual +4 oxidation state is a consequence of the high reaction barriers of the singlet or triplet potential surfaces constrained by the global dispersion attraction and the great steric demands of the norbornyl groups. The much more limited stability of the corresponding cyclohexyl derivative (cx)4Fe may result from the conical intersection between the singlet potential surface and the quintet spin potential surface arising from the weaker dispersion attraction and the reduced steric effect of the cyclohexyl groups relative to the 1-norbornyl groups. In contrast, the high stability of the likewise experimentally known (cx)4M (M = Ru or Os) structures results from the larger ligand field splitting (Δ) of the d-orbital energies for the second and third-row transition metals ruthenium and osmium relative to that of the first-row transition metal iron. The cyclohexyl derivative (cx)4Fe is predicted to be reactive toward carbon monoxide to insert CO into up to two Fe-C bonds. However, the dispersion effect as well as the much larger size of the 1-norbornyl substituents prevents similar reactivity of (nor)4Fe with carbon monoxide.

Synthesis of Methanesulfonic Acid Directly from Methane: The Cation Mechanism or the Radical Mechanism?

Abstract: In 2019, Diaz-Urrutia and Ott developed a high-yield method for direct conversion of methane to methanesulfonic acid and proposed a cationic chain reaction mechanism. However, Roytman and Singleton questioned this mechanism, and they favored a free-radical mechanism. In the present paper, we studied both the cationic chain and radical mechanisms and found the radical mechanism is more favorable, since it has a much lower energy barrier. However, the radical mechanism has not considered the effect of ions for the reaction taking place in oleum. Thus, we studied a simple model of a protonated radical mechanism, which further lowers the energy barrier. Although the true mechanism for the CH4 + SO3 reaction could be more complicated in electrolyte solutions, this model should be helpful for the further study of the mechanism of this reaction.

Beyond Steric Crowding: Dispersion Energy Donor Effects in Large Hydrocarbon Ligands.

Abstract: ConspectusInteractions between sterically crowded hydrocarbon-substituted ligands are widely considered to be repulsive because of the intrusion of the electron clouds of the ligand atoms into each other's space, which results in Pauli repulsion. Nonetheless, there is another interaction between the ligands which is less widely publicized but is always present. This is the London dispersion (LD) interaction which can occur between atoms or molecules in which dipoles can be induced instantaneously, for example, between the H atoms from the ligand C-H groups.These LD interactions are always attractive, but their effects are not as widely recognized as those of the Pauli repulsion despite their central role in the formation of condensed matter. Their relatively poor recognition is probably due to the relative weakness (ca. 1 kcal mol-1) of individual H···H interactions owing to their especially strong distance dependence. In contrast, where there are numerous H···H interactions, a collective LD energy equaling several tens of kcal mol-1 may ensue. As a result, in some molecules the latent importance of the LD attraction energies emerges and assumes a prominence that can overshadow the Pauli effects (e.g., in the stabilization of high-oxidation-state transition-metal alkyls, inducing disproportionation reactions, or in the stabilization of otherwise unstable bonds).Despite being known for over a century, the accurate quantification of individual H···H LD effects in molecular species is a relatively recent phenomenon and at present is based mainly on modified DFT calculations. A few leading reviews summarized these earlier studies of the C-H···H-C LD interactions in organic molecules, and their effects on the structures and stabilities were described. LD effects in sterically crowded inorganic and organometallic molecules have been recognized.The author's interest in these LD effects arose fortuitously over a decade ago during research on sterically crowded heavier main-group element carbene analogues and two-coordinate, open-shell (d1-d9) transition-metal complexes where counterintuitive steric effects were observed. More detailed explanations of these effects were provided by dispersion-corrected DFT calculations in collaboration with the groups of Tuononen and Nagase (see below).This Account describes our development of these initial results for other inorganic molecular classes. More recently, the work has led us to move to the planned inclusion of dispersion effects in ligands to stabilize new molecular types with theoretical input from the groups of Vasko and Grimme (see below). Our approach sought to use what Grimme has described as dispersion effect donor (DED) groups (i.e., spatially close-lying, densely packed substituents either as ligands (e.g., -C6H2-2,4,6-Cy3, Cy = cyclohexyl) or as parts of ligands (e.g., a Cy substituent) that produce relatively large dispersion energies to stabilize these new compounds.We predict that the future design of sterically crowding hydrocarbon ligands will include the consideration and incorporation of LD effects as a standard methodology for directed use in the attainment of new synthetic targets.

Research on the Influence of the Interfacial Properties Between a Cu3BiS3 Film and an In x Cd1− x S Buffer Layer for Photoelectrochemical Water Splitting

Abstract: The ternary compound photovoltaic semiconductor Cu3BiS3 thin film‐based photoelectrode demonstrates a quite promising potential for photoelectrochemical hydrogen evolution. The presented high onset potential of 0.9 VRHE attracts much attention and shows that the Cu3BiS3 thin films are quite good as an efficient solar water splitting photoelectrode. However, the CdS buffer does not fit the Cu3BiS3 thin film: the conduction band offset between CdS and Cu3BiS3 reaches 0.7 eV, and such a high conduction band offset (CBO) significantly increases the interfacial recombination ratio and is the main reason for the relatively low photocurrent of the Cu3BiS3/CdS photoelectrode. In this study, the InxCd1−xS buffer layer is found to be significantly lowered the CBO of CBS/buffer and that the In incorporation ratio of the buffer influences the CBO value of the CBS/buffer. The Pt‐TiO2/In0.6Cd0.4S/Cu3BiS3 photocathode exhibits an appreciable photocurrent density of ≈12.20 mA cm−2 at 0 VRHE with onset potential of more than 0.9 VRHE, and the ABPE of the Cu3BiS3‐based photocathode reaches the highest value of 3.13%. By application of the In0.6Cd0.4S buffer, the Cu3BiS3‐BiVO4 tandem cell presents a stable and excellent unbiased STH of 2.57% for over 100 h.

Charge Separation Enhancement Enables Record Photocurrent Density in Cu2ZnSn(S,Se)4 Photocathodes for Efficient Solar Hydrogen Production

Abstract: Cu2ZnSn(S,Se)4 (CZTSSe) is a promising light absorbing semiconductor for solar energy conversion in photovoltaic cells and photo‐electrochemical (PEC) water‐splitting devices, owing to its earth‐abundant constituents, adjustable band‐gap, and superior absorption coefficient. However, the severe charge carrier recombination and the sluggish charge separation efficiency are the main issues obstructing the enhancement of device performance. In this work, a planar‐type Mo/CZTSSe/CdS/TiO2/Pt photocathode is fabricated. High‐quality CZTSSe film with compact and uniform crystal grains can be obtained via a two‐step process involving solution processed spin coating and thermally processed selenization. When an appropriate film thickness is used, both bulk defects and surface/interface defects are passivated, significantly suppressing the defects‐assisted recombination. Moreover, the benign energy band alignment of CZTSSe/CdS heterojunction is favorable to enhance photo‐generated charge separation and transfer efficiency. A remarkable photocurrent density of 40.40 mA cm−2 (at 0 VRHE) can be achieved, approaching to its theoretical value of 42.85 mA cm−2, and representing the highest value reported to date for kesterites‐based photocathodes. A champion CZTSSe photocathode with half‐cell solar‐to‐hydrogen conversion efficiency of 6.47% suggests a bright future for efficient solar hydrogen production applications.

Process Accumulated 8% Efficient Cu2ZnSnS4‐BiVO4 Tandem Cell for Solar Hydrogen Evolution with the Dynamic Balance of Solar Energy Storage and Conversion

Abstract: A process accumulated record solar to hydrogen (STH) conversion efficiency of 8% is achieved on the Cu2ZnSnS4‐BiVO4 tandem cell by the synergistic coupling effect of solar thermal and photoelectrochemical (PEC) water splitting with the dynamic balance of solar energy storage and conversion of the greenhouse system. This is the first report of a Cu2ZnSnS4‐BiVO4 tandem cell with a high unbiased STH efficiency of over 8% for solar water splitting due to the greenhouse device system. The greenhouse acts as a solar thermal energy storage cell, which absorbs infrared solar light and storage as thermal energy with the solar light illumination time, while thermoelectric device (TD) converts thermal energy into electric power, electric power is also recycled and added onto Cu2ZnSnS4‐BiVO4 tandem cell for enhanced overall water splitting. Finally, the solar water splitting properties of the TD‐Cu2ZnSnS4‐BiVO4 integrated tandem cell in pure natural seawater are demonstrated, and a champion STH efficiency of 2.46% is presented, while a large area (25 cm2) TD‐Cu2ZnSnS4‐BiVO4 integrated tandem device with superior long‐term stability is investigated for 1 week, which provides new insight into photoelectrochemical solar water splitting devices.