Metal-seed assistant photodeposition of platinum over Ta_(3)N_(5) photocatalyst for promoted solar hydrogen production under visible light

Cocatalysts play a vital role in accelerating the reaction kinetics and improving the charge separation of photocatalysts for solar hydrogen production.The promotion of the photocatalytic activity largely relies on the loading approach of the cocatalysts.Herein,we introduce a metal-seed assistant photodeposition approach to load the hydrogen evolution cocatalyst of platinum onto the surface of Ta_(3)N_(5) photocatalyst,which exhibits about 3.6 times of higher photocatalytic proton reduction activity with respect to the corresponding impregnation or photodeposition loading.Based on our characterizations,the increscent contact area of the cocatalyst/semiconductor interface with metal-seed assistant photodeposition method is proposed to be responsible for the promoted charge separation as well as enhanced photocatalytic H2 evolution activity.It is interesting to note that this innovative deposition strategy can be easily extended to loading of platinum cocatalyst with other noble or non-noble metal seeds for promoted activities,demonstrating its good generality.Our work may provide an alternative way of depositing cocatalyst for better photocatalytic performances.

Perovskite–A wonder catalyst for solar hydrogen production

Hydrogen generation via artificial photosynthesis paves a promising way to remit the ever-increasing energy crisis and deteriorative environmental issues.Among all the materials utilized for solar hydrogen production,perovskite has emerged as a rising star due to its superior optoelectronic properties.This manuscript aims to provide a comprehensive review summarizing the recent inspiring advancements on perovskite-based solar hydrogen production systems,including the particulate photocatalysis,photoelectrochemical cells,and photovoltaic-electrocatalytic cells.We start with a brief introduction of the advantages of perovskites for solar hydrogen production and the basic principles of the three most prominent solar hydrogen production systems.The representative progresses in this field are then detailed with a special emphasis on the strategies to improve the efficiency and the stability of the systems.Finally,challenges and opportunities for the further development of the PVK-based solar hydrogen production systems are presented with perspective given on outlook,performance,cost and stability.

Defect and interface control on graphitic carbon nitrides/upconversion nanocrystals for enhanced solar hydrogen production

The effective utilization of solar energy for hydrogen production requires an abundant supply of thermodynamically active photo-electrons;however,the photocatalysts are generally impeded by insufficient light absorption and fast photocarrier recombination.Here,we report a multiple-regulated strategy to capture photons and boost photocarrier dynamics by devel-oping a broadband photocatalyst composed of defect engineered g-C_(3)N_(4)(DCN)and upconversion NaYF4:Yb^(3+),Tm^(3+)(NYF)nanocrystals.Through a precise defect engineering,the S dopants and C vacancies jointly render DCN with defect states to effectively extend the visible light absorption to 590 nm and boost photocarrier separation via a moderate electron-trapping ability,thus facilitating the subsequent re-absorption and utilization of upconverted photons/electrons.Importantly,we found a promoted interfacial charge polarization between DCN and NYF has also been achieved mainly due to Y-N interaction,which further favors the upconverted excited energy transfer from NYF onto DCN as verified both theoretically and experimentally.With a 3D architecture,the NYF@DCN catalyst exhibits a superior solar H2 evolution rate among the reported upconversion-based system,which is 19.3 and 1.5 fold higher than bulk material and DCN,respectively.This work provides an innovative strategy to boost solar utilization by using defect engineering and building up interaction between hetero-materials.

A Solar Energy System Design for Green Hydrogen Production in South-Western Nigeria, Lagos State, Using HOMER & ASPEN

Solar system design for green hydrogen production has become the most prominent renewable energy research area, and this has also actively fueled the desire to achieve net-zero emissions. Hydrogen is a promising energy carrier because it possesses more energy capacity than fossil fuels and the abundant nature of renewable energy systems can be utilized for green hydrogen production. However, the design of an optimized electrical energy system required for hydrogen production is crucial. Solar energy is indeed beneficial for green hydrogen production and this research designed, discussed, and provided high-level research on HOMER design for green hydrogen production and deployed the energy requirement with ASPEN Plus to optimize the energy system, while also incorporating fuzzy logic and PID control approaches. In addition, a promising technology with a high potential for renewable hydrogen energy is the proton exchange membrane (PEM) electrolyzer. Since its cathode (hydrogen electrode) may be operated over a wide range of pressure, a control process must be added to the system in order for it to work dynamically efficiently. This system can be characterized as an analogous circuit that consists of a resistor, capacitor, and reversible voltage. As a result, this research work also explores the Fuzzy-PID control of the PEM electrolysis system. Both the PID and Fuzzy Logic control systems were simulated using the control simulation program Matlab R2018a, which makes use of Matlab script files and the Simulink environment. Based on the circuit diagram, a transfer function that represents the mathematical model of the plant was created, and the PEM electrolysis control system is determined to be highly significant and applicable to the two control systems. The PI controller, however, has a 30.8% overshoot deficit, but when the fuzzy control system is compared to the PID controller, it is found that the fuzzy control system achieves stability more quickly, demonstrating its benefit over PID.

Defect engineering of ternary Cu-In-Se quantum dots for boosting photoelectrochemical hydrogen generation

Heavy-metal-free ternary Cu–In–Se quantum dots(CISe QDs)are promising for solar fuel production because of their low toxicity,tunable band gap,and high light absorption coefficient.Although defects significantly affect the photophysical properties of QDs,the influence on photoelectrochemical hydrogen production is not well understood.Herein,we present the defect engineering of CISe QDs for efficient solar-energy conversion.Lewis acid–base reactions between metal halide–oleylamine complexes and oleylammonium selenocarbamate are modulated to achieve CISe QDs with the controlled amount of Cu vacancies without changing their morphology.Among them,CISe QDs with In/Cu=1.55 show the most outstanding photoelectrochemical hydrogen generation with excellent photocurrent density of up to 10.7 mA cm-2(at 0.6 VRHE),attributed to the suitable electronic band structures and enhanced carrier concentrations/lifetimes of the QDs.The proposed method,which can effectively control the defects in heavy-metal-free ternary QDs,offers a deeper understanding of the effects of the defects and provides a practical approach to enhance photoelectrochemical hydrogen generation.

Effect of ZnO Electrodeposited on Carbon Film and Decorated with Metal Nanoparticles for Solar Hydrogen Production

In this study, we prepared horn-like ZnO structures on carbon films（ZnO/CF） by electrodeposition and decorated the ZnO horns with different metals（Ag, Au, and Pt） via photodeposition（M-ZnO/CF）. Using M-ZnO/CF as photocatalysts, we examined ways to enhance solar hydrogen production from various points of view, such as modifying the intrinsic physical properties and thermodynamics of the materials, and varying the chemical environment during M-ZnO/CF fabrication. In particular, we focused on the effects of the carbon film and metals in M-ZnO/CF hybrid photocatalysts on solar hydrogen production. The type of metal nanoparticles is an important factor in solar hydrogen production because the deposition rate and electrical conductivity of each metal affect the proton-water reduction ability.

Efficient solar fuel production enabled by an iodide oxidation reaction on atomic layer deposited MoS_(2)

Oxygen evolution reaction(OER)as a half-anodic reaction of water splitting hinders the overall reaction efficiency owing to its thermodynamic and kinetic limitations.Iodide oxidation reaction(IOR)with low thermodynamic barrier and rapid reaction kinetics is a promising alternative to the OER.Herein,we present a molybdenum disulfide(MoS_(2))electrocatalyst for a high-efficiency and remarkably durable anode enabling IOR.MoS_(2)nanosheets deposited on a porous carbon paper via atomic layer deposition show an IOR current density of 10 mA cm^(–2)at an anodic potential of 0.63 V with respect to the reversible hydrogen electrode owing to the porous substrate as well as the intrinsic iodide oxidation capability of MoS_(2)as confirmed by theoretical calculations.The lower positive potential applied to the MoS_(2)-based heterostructure during IOR electrocatalysis prevents deterioration of the active sites on MoS_(2),resulting in exceptional durability of 200 h.Subsequently,we fabricate a two-electrode system comprising a MoS_(2)anode for IOR combined with a commercial Pt@C catalyst cathode for hydrogen evolution reaction.Moreover,the photovoltaic–electrochemical hydrogen production device comprising this electrolyzer and a single perovskite photovoltaic cell shows a record-high current density of 21 mA cm^(–2)at 1 sun under unbiased conditions.

Theoretical assessment of hydrogen production and multicycle energy conversion via solar thermochemical cycle based on nonvolatile SnO2

A kind of solar thermochemical cycle based on methanothermal reduction of SnO2 is proposed for H2 and CO production. We find that the oxygen release capacity and thermodynamic driven force for methanothermal reduction of SnO2 are large, and suggest CH4 :SnO2 = 2:1 as the feasible reduction condition for achieving high purities of syngas and avoiding vaporization of produced Sn. Subsequently, the amount of H2 and energetic upgrade factors under different oxidation conditions are compared, in which excess water vapor is found beneficial for hydrogen production and fuel energetic upgradation. Moreover, the effect of incom plete recovery of SnO2 on the subsequent cycle is underscored and explained. After accounting for factors such as isothermal operation and cycle stability, CH4 :SnO2 = 2:1 and H2O:Sn = 4:1 are suggested for highest solar-to-fuel efficiency of 46.1% at nonisothermal condition, where the reduction and oxidation temperature are 1400 and 600 K, respectively.

Impact of Heat Transfer Media on Performance of Solar-Hydrogen Power Generation

Solar-hydrogen system has great potential for contributing to sustainable and clean energy supply. The aim of this study is to clarify the impact of heat transfer media in solar collector such as methane, ammonium, hydrogen, air and water on the performance of solar-hydrogen system. After estimating the highest temperature attainable by each heat transfer media, the amount of thermal energy that could be saved in the production of hydrogen or preheat for power generation by fuel cell was calculated. The power generation performance of fuel cell using each heat transfer media was also investigated. As a result, it has been revealed that the temperature changes of methane, ammonium and air follow the horizontal solar radiation intensity irrespective of seasons, and their highest temperatures are almost the same among them. The temperature response of hydrogen is slower than methane, ammonium and air. This study defines the ratio of saving thermal energy which indicates the effect of solar thermal utilization for production of hydrogen or preheat for power generation by fuel cell without using utility gas. It has been found that the biggest thermal energy saving is obtained when hydrogen and air are used as the heat transfer media. The power generated by PEFC system per effective area of evacuated tube collector in the case of using methane or ammonium is 3.309×10-2 kWh/m2 and 2.076×10-2 kWh/m2, respectively, while it is 2.466×10-2 kWh in the case of using hydrogen and air.

Global Solar Variations and Effects of Relativistic 2D-Hydrogen

Characteristics of the temporal evolution of the global solar magnetic field were found to display a 2-step cycling mode consistent with a pattern of a fundamental harmonic progression underlying all solar cycles at all times and having its seat in the fusion region of the core via nuclear magnetic resonance as part of the hydrogen and helium fusion chain. In addition to the three principal zones in the interior of the sun, core, radiative zone, and convection zone, a sub-surface layer is being suggested to take part in the processes of varying solar activity, which would be an extension of relativistic 2D hydrogen being formed throughout the plasma body under the influence of pressure waves originating in the core. The major participants confined to such a 2D layer is for the most part 2D hydrogen particularly in its form of relativistic 2D hydrogen, where the Bohratom binding energies are replaced by binding energies in the range of Eo = 0.5 MeV. For this reason it is conjectured that this condition lends itself to providing contributions to (a) the energy release including 0.5 MeV and lower energy γ-photons as well as (b) superimposing a radial component to the global dipole field.

光催化制备过氧化氢的研究进展

过氧化氢是一种高价值、多功能的绿色化学品,被广泛应用于各种工业生产以及清洁能源燃料等领域。传统蒽醌法制备过氧化氢的工艺不仅能耗巨大,且会产生各种化学废料,环境污染较大。光催化技术是近年来生产H_(2)O_(2)的一种绿色环保和发展前景广阔的新方法,但其仍受制于光催化活性较低、H_(2)O_(2)产量较低和反应较慢等问题。简要阐述了光催化制备H_(2)O_(2)基本原理,介绍了光催化制备H_(2)O_(2)的研究进展,对比分析了不同光催化材料的结构及光催化性能,归纳总结了光催化材料的结构调控及性能提高途径和策略,提出了存在的问题,并展望了未来的发展方向。

Potential for Green Hydrogen Production from Biomass, Solar and Wind in Togo

Potential of green hydrogen producing from biomass, solar and wind in Togo has been performed. The availability of these three resources has been depicted with maps showing them per cantons in Togo, thus, by using the datasets from ESA Biomass Climate Change Initiative, the global solar atlas and the global wind atlas. The conversions rates used were: for solar resource, 3% of land was allocated for the analysis after removing the exclusions with a conversion rate of 52.5 kWh/kg of hydrogen;for biomass hydrogen, the conversion rate of 13.4 kg BS/kg H2 was assumed. Wind resources at 50 m above ground were not sufficient to evaluate the potential as it is lower than class 3 winds. QGIS version 3.6.4 and R version 4.0.4 were used. Results showed that biomass is the leading resource for producing green hydrogen from renewable energy resources;with good impact in these two cantons: Bassar, Gobe/ Eketo/Gbadi N’Kugna. However, this resource is still decreasing and in some cantons it is null.

Research on the optimum hydrogenated silicon thin films for application in solar cells

Hydrogenated silicon （Si：H） thin films for application in solar ceils were deposited by using very high frequency plasma enhanced chemical vapour deposition （VHF PECVD） at a substrate temperature of about 170 ℃, The electrical, structural, and optical properties of the films were investigated. The deposited films were then applied as i-layers for p-i-n single junction solar cells. The current-voltage （I - V） characteristics of the cells were measured before and after the light soaking. The results suggest that the films deposited near the transition region have an optimum properties for application in solar cells. The cell with an i-layer prepared near the transition region shows the best stable performance.

基于参数自适应随机模型预测控制的风光氢耦合系统功率调控策略

针对风光氢耦合系统源荷两侧不确定性对其系统功率平衡造成的影响,提出了一种基于场景分析法的参数自适应随机模型预测控制功率调控策略。根据风光氢耦合系统的能源供给架构建立了描述其动态特性的线性离散状态空间模型;通过场景分析法对系统不确定性进行描述,作为参数自适应随机模型预测控制的输入;在设计的参数自适应随机模型预测控制优化框架下,计及延长系统设备生命周期的目标进行优化。针对随机模型预测控制在优化过程中预测时域和控制时域固定不变的缺陷,提出参数自适应方法以获取更好的优化效果。结果表明:在优化系统功率平衡方面,所提控制策略相较于随机模型预测控制提高了6.25百分点;在减少可控设备大功率运行方面,所提策略相较于常规模型预测控制降低了60%,验证了所提策略能够有效解决风光氢耦合系统源荷两侧的不确定性。

基于模型预测控制的光-氢-储耦合系统的功率优化分配方法研究

针对光伏发电存在间歇性和波动性问题,对光—氢—储耦合系统的控制策略进行研究,提出一种模型预测控制(MPC)的“光—氢—储”功率分配方法。首先,构建出光—氢—储耦合系统的整体结构,其中,氢能源系统包括PEM电解槽、氢燃料电池和储氢罐,其次,根据光—氢—储耦合系统的功率平衡方程,构建出状态空间模型,以PEM电解槽功率、氢燃料电池功率作为控制量,明确系统中的多种约束条件,将MPC优化问题调整为二次规划(QP)问题进行求解,利用s-function函数模块构建MPC控制器,完成了系统的闭环仿真。通过仿真分析,验证了所提MPC实时功率分配方法的有效性。

光热驱动的膜分离生物甲烷制氢过程建模与仿真分析

光热驱动的甲烷重整制氢技术,是将太阳能转化为燃料的主要技术路径之一。引入聚光集热技术,可实现太阳能的全光谱利用,有效提高太阳能到燃料化学能的转化效率,同时显著降低系统能耗及碳排放。将多孔碳化硅吸热体和La_(1-x)Sr_(x)Co_(1-y)Fe_(y)O_(3-δ)钙钛矿透氧膜结合,提出一种光热驱动的膜反应制氢的设计思路,实现了连续、高效的制氢过程。完成了该反应过程的概念设计,建立考虑辐射-传热-膜分离-反应的数值模型并进行仿真模拟;重点评估了膜表面的温度均匀性,并分析温度对膜内反应及出口产物的影响规律。结果表明,该模型可以有效精准描述概念设计过程。研究成果可为光热驱动的高温膜反应器设计和放大提供理论依据以及初步设计方法。

n-nc-Si:H低温制备工艺及其在柔性钙钛矿太阳电池中的应用

【目的】为在低温工艺下制备出适用于柔性钙钛矿太阳电池的高性能电子传输层,需要对电子传输层材料及制备条件进行研究。【方法】将n型氢化纳米晶硅薄膜作为柔性钙钛矿太阳电池电子传输层,研究衬底温度对薄膜性能的影响,并优化电子传输层与钙钛矿层界面处理工艺和结构。【结果】得到暗电导率、光透过率、表面形貌适用于柔性钙钛矿太阳电池电子传输层的n型氢化纳米晶硅薄膜低温制备条件,经过界面优化处理的柔性钙钛矿太阳电池转换效率达到14.66%。【结论】在低温工艺下制备出了高性能的电子传输层及柔性钙钛矿太阳电池,对进一步开展叠层钙钛矿太阳电池的研究具有指导意义。

太阳能光热催化制氢研究进展

太阳能光热催化(SPTC)制氢技术是从遵循全光谱太阳能分波段能量禀赋特性出发,利用太阳能短波部分高品位光子的光效应驱动光催化反应,同时利用长波部分低品位光子的热效应驱动热催化反应或者辅助强化光催化制氢,可解决传统热催化的高能耗和光催化的低转化效率问题,实现全光谱太阳能的分波段协调转化高效制氢。本文首先介绍了SPTC的定义与分类,然后详细综述了热效应对光催化以及光效应对热催化的协同强化机制,最后对SPTC技术的发展前景进行展望,以期为该技术更广泛的研究及应用提供指导。

基于8760h生产模拟的离网风光储氢系统规划方法

建设离网型风光可再生能源制氢系统,能够有效实现可再生能源的就地消纳,降低电网建设压力,是符合我国“双碳”目标、促进绿色工业发展的重要技术路径。在缺乏大电网支撑的离网园区规划中,实现基于全年8760h生产模拟的规划求解,合理配置碱液与质子交换膜两种类型制氢设备,是应对风光波动、高效经济制氢的重要技术问题。因此,该文针对离网风光储氢园区规划方法展开研究,提出基于8760h生产模拟的规划模型,并通过模型转化与改进Benders分解实现模型求解。首先,建立考虑不同电制氢设备动态特性差异的离网风光储氢系统运行规划一体化模型。进一步,对上层规划主问题模型引入公共运行变量,对运行层子问题进行逐月拆分,降低原始规划模型求解难度,基于改进Benders分解法实现模型求解。最后,通过山东潍坊地区实际算例,验证所提离网风光储氢系统规划方法能够实现基于8760h生产模拟的设备容量规划,合理配置具有不同运行性能的制氢设备,提高离网制氢系统的经济性。