Abstract
We report a scalable and reproducible method for reactive co‐sputtering of Mo‐doped BiVO
4
thin films with broad compositional control. Optimal photoanode performance is achieved at a Mo ...concentration of 3 at. %. Incorporation of Mo promotes growth of large grains and reduces majority carrier transport limitations, resulting in maximum AM1.5G photocurrent densities of 3.5 mA cm
−2
at 1.23 V vs. RHE in pH 6.8 buffer solution containing 0.1
M
Na
2
SO
3
as a hole scavenger. Operation as a front‐illuminated water oxidation photoanode is achieved by balancing the operational stability, catalytic activity, and parasitic optical absorption of a FeOOH oxygen evolution catalyst. FeOOH/Mo:BiVO
4
thin film photoanodes enable water oxidation under the front‐side illumination conditions used in integrated tandem water splitting devices.
This paper compares several approximate methods for calculating rate coefficients for the O(3P) + HCl reaction to presumably more accurate quantum mechanical calculations that are based on applying ...the J-shifting approximation (QM/JS) to an accurate cumulative reaction probability for J = 0. All calculations for this work employ the recent S4 potential energy surface, which presents a number of challenges for the approximate methods. The O + HCl reaction also poses a significant challenge to computational dynamics because of the heavy−light−heavy mass combination and the broad noncollinear reaction path. The approximate methods for calculating the thermal rate coefficient that are examined in this article are quasiclassical trajectories (QCT), conventional transition state theory (TST), variational transition state theory employing the improved canonical variational theory (ICVT), ICVT with the microcanonical optimized multidimensional tunneling correction (ICVT/μOMT), and reduced dimensionality quantum mechanical calculations based on adiabatic bend and J-shifting (QM/AB-JS) approximations. It is seen that QCT, TST, and ICVT rate coefficients agree with each other within a factor of 2.7 at 250 K and 1.6 at l000 K, whereas inclusion of tunneling by the ICVT/μOMT, QM/AB-JS, or QM/JS methods increases the rate coefficients considerably. However, the ICVT/μOMT and QM/AB-JS methods yield significantly lower rate coefficients than the QM/JS calculations, especially at lower temperatures. We also report and discuss calculations for the state-selected reaction of O(3P) with HCl in the first excited vibrational state. In addition to the dynamics calculations, we report new electronic structure calculations by the Multi-Coefficient Gaussian-3 (MCG3) method that indicate that one possible source of disagreement between the QM/JS rate coefficients and experiment is that the barrier on the S4 surface may be too narrow.
Automatic facial gender recognition is a widely used task in the field of computer vision, which is very easy for a human, but very challenging for computers. In this paper, a face gender ...classification algorithm based on face recognition feature vectors is proposed. Firstly, face detection and preprocessing are performed on the input images, and the faces are adjusted to a unified format. Secondly, the face recognition model is used to extract feature vectors as the representation of the face in the feature space. Finally, machine learning methods are used to classify the extracted feature vector. Meanwhile, this study uses t-distributed Stochastic Neighbor Embedding (T-SNE) to visualize the face recognition feature vectors to verify the effectiveness of the face recognition feature vectors on the issue of gender classification. The proposed method has achieved a recognition rate of 99.2% and 98.7% on the FEI dataset and the SCIEN dataset, respectively. Besides, it also achieves a recognition rate of 97.4% on the Asian star face dataset, outperforming existing methods, which shows that the proposed method is helpful for the research of facial gender.
We demonstrate an InP heterojunction solar cell employing an ultrathin layer (∼10 nm) of amorphous TiO
deposited at 120 °C by atomic layer deposition as the transparent electron-selective contact. ...The TiO
film selectively extracts minority electrons from the conduction band of p-type InP while blocking the majority holes due to the large valence band offset, enabling a high maximum open-circuit voltage of 785 mV. A hydrogen plasma treatment of the InP surface drastically improves the long-wavelength response of the device, resulting in a high short-circuit current density of 30.5 mA/cm
and a high power conversion efficiency of 19.2%.
Solar water splitting refers to the reaction that converts solar energy into chemical fuel. It is an attractive means to store solar energy. This process, analogous to nature photosynthesis, uses ...semiconductor to capture and convert solar irradiation and, as such, is called artificial photosynthesis. Despite its promising prospect, the lack of materials that can satisfy all requirements to achieve efficient solar water splitting becomes an important challenge. In this thesis, we aim to develop a strategy of forming heteronanostructure to tackle the challenge faced by metal oxide-based photoanode for water oxidation. The challenge associated with metal oxide-based photoanodes and current approach to alleviate the challenge is first discussed. We propose a strategy of combining multiple components to form heteronanostructure to meet the challenges, in particular the charge transport issue. By introducing a dedicated charge transporter, we fabricate various heteronanostructure including TiO2 /TiSi2, Fe2O3/TiSi2 and Fe2O3/AZO nanotubes to improve the charge collection and therefore overall efficiency. Additionally, the growth of several important metal oxides by atomic layer deposition is developed and its utilization as photoanode for water splitting is studied for the first time. Because this strategy is based on the rational design and synthesis of materials, it has the potential to produce electrodes with a combination of properties that have not been exhibited simultaneously by single-component materials. In addition, the strategy is highly versatile and can incorporate the latest developments produced by parallel efforts. We are confident that the rational design and synthesis of materials such as the strategy proposed here will play an increasingly more important role in energy research.
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