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Hydrogen is readily obtained from renewable and non‐renewable resources via water splitting by using thermal, electrical, photonic and biochemical energy. The major hydrogen production is generated from thermal energy through steam reforming/gasification of fossil fuel. As the commonly used non‐renewable resources will be depleted in the long run, there is great demand to utilize renewable energy resources for hydrogen production. Most of the renewable resources may be used to produce electricity for driving water splitting while challenges remain to improve cost‐effectiveness. As the most abundant energy resource, the direct conversion of solar energy to hydrogen is considered the most sustainable energy production method without causing pollutions to the environment. In overall, this review briefly summarizes thermolytic, electrolytic, photolytic and biolytic water splitting. It highlights photonic and electrical driven water splitting together with photovoltaic‐integrated solar‐driven water electrolysis. Energy‐driven hydrogen production via water splitting with thermal, electrical, photonic and biochemical energy and their combined forms such as thermoelectrolysis, biophotolysis, and photoelectrolysis are summarized in this review. There are focuses on recent advances in water splitting with the use of renewable energy for photocatalytic and electrocatalytic hydrogen production such as photovoltaic‐integrated solar driven water electrolysis.

In this paper, we first introduce a multi-step inertial Krasnosel’skiǐ–Mann algorithm (MiKM) for nonexpansive operators in real Hilbert spaces. We give the convergence of the MiKM by investigating the convergence of the Krasnosel’skiǐ–Mann algorithm with perturbations. We also establish global pointwise and ergodic iteration complexity bounds of the Krasnosel’skiǐ–Mann algorithm with perturbations. Based on the MiKM, we construct some multi-step inertial splitting methods, including the multi-step inertial Douglas–Rachford splitting method (MiDRS), the multi-step inertial forward–backward splitting method, multi-step inertial backward–forward splitting method and and the multi-step inertial Davis–Yin splitting method. Numerical experiments are provided to illustrate the advantage of the MiDRS over the one-step inertial DRS and the original DRS.

While \"splitting\" is a familiar concept, its meaning is not as self-evident as is commonly assumed. In different contexts, it refers to different phenomena and is supported by different understandings of psychic dynamics. In this paper, the author presents four different conceptualizations of splitting, which capture the essential aspects of contemporary psychoanalytic discourse on the concept. There is a dissociative kind of splitting, which involves splitting off, in the face of trauma, whole personalities, which to some extent remain accessible to consciousness; there is a disavowal kind of splitting that splits off our awareness of disturbing realities or their meanings in our efforts to avoid the inner restraints imposed by repression; and there are two forms of splitting of the object into good and bad-one focusing on the splitting of representations of the object due to ego weakness and environmental determinants, and the other on the splitting of the mind itself in a primarily destructive act aimed at sparing the good from the destructiveness of our death instinct. All four conceptualizations have their origins in Freud's writing and then are further developed in the work of later analysts. The author argues that understanding the nature of these various conceptualizations of splitting can contribute to analytic theory and practice. It also sheds light on the essential nature of analytic approaches and how they offer different perspectives on the unity and disunity of man's basic nature.

Electrolysis of water to generate hydrogen fuel is an attractive renewable energy storage technology. However, grid-scale fresh-water electrolysis would put a heavy strain on vital water resources. Developing cheap electrocatalysts and electrodes that can sustain seawater splitting without chloride corrosion could address the water scarcity issue. Here we present a multilayer anode consisting of a nickel–iron hydroxide (NiFe) electrocatalyst layer uniformly coated on a nickel sulfide (NiSx) layer formed on porous Ni foam (NiFe/NiSx-Ni), affording superior catalytic activity and corrosion resistance in solar-driven alkaline seawater electrolysis operating at industrially required current densities (0.4 to 1 A/cm²) over 1,000 h. A continuous, highly oxygen evolution reactionactive NiFe electrocatalyst layer drawing anodic currents toward water oxidation and an in situ-generated polyatomic sulfate and carbonate-rich passivating layers formed in the anode are responsible for chloride repelling and superior corrosion resistance of the salty-water-splitting anode.

Solar fuel generation from thermochemical H2O or CO2 splitting is a promising and attractive approach for harvesting fuel without CO2 emissions. Yet, low conversion and high reaction temperature restrict its application. One method of increasing conversion at a lower temperature is to implement oxygen permeable membranes (OPM) into a membrane reactor configuration. This allows for the selective separation of generated oxygen and causes a forward shift in the equilibrium of H2O or CO2 splitting reactions. In this research, solar-driven fuel production via H2O or CO2 splitting with an OPM reactor is modeled in isothermal operation, with an emphasis on the calculation of the theoretical thermodynamic efficiency of the system. In addition to the energy required for the high temperature of the reaction, the energy required for maintaining low oxygen permeate pressure for oxygen removal has a large influence on the overall thermodynamic efficiency. The theoretical first-law thermodynamic efficiency is calculated using separation exergy, an electrochemical O2 pump, and a vacuum pump, which shows a maximum efficiency of 63.8%, 61.7%, and 8.00% for H2O splitting, respectively, and 63.6%, 61.5%, and 16.7% for CO2 splitting, respectively, in a temperature range of 800 °C to 2000 °C. The theoretical second-law thermodynamic efficiency is 55.7% and 65.7% for both H2O splitting and CO2 splitting at 2000 °C. An efficient O2 separation method is extremely crucial to achieve high thermodynamic efficiency, especially in the separation efficiency range of 0–20% and in relatively low reaction temperatures. This research is also applicable in other isothermal H2O or CO2 splitting systems (e.g., chemical cycling) due to similar thermodynamics.

Production of hydrogen fuel from sunlight and water, two of the most abundant natural resources on Earth, offers one of the most promising pathways for carbon neutrality 1 – 3 . Some solar hydrogen production approaches, for example, photoelectrochemical water splitting, often require corrosive electrolyte, limiting their performance stability and environmental sustainability 1 , 3 . Alternatively, clean hydrogen can be produced directly from sunlight and water by photocatalytic water splitting 2 , 4 , 5 . The solar-to-hydrogen (STH) efficiency of photocatalytic water splitting, however, has remained very low. Here we have developed a strategy to achieve a high STH efficiency of 9.2 per cent using pure water, concentrated solar light and an indium gallium nitride photocatalyst. The success of this strategy originates from the synergistic effects of promoting forward hydrogen–oxygen evolution and inhibiting the reverse hydrogen–oxygen recombination by operating at an optimal reaction temperature (about 70 degrees Celsius), which can be directly achieved by harvesting the previously wasted infrared light in sunlight. Moreover, this temperature-dependent strategy also leads to an STH efficiency of about 7 per cent from widely available tap water and sea water and an STH efficiency of 6.2 per cent in a large-scale photocatalytic water-splitting system with a natural solar light capacity of 257 watts. Our study offers a practical approach to produce hydrogen fuel efficiently from natural solar light and water, overcoming the efficiency bottleneck of solar hydrogen production. Photocatalytic water splitting with a high solar-to-hydrogen efficiency of more than nine per cent is achieved using pure water, concentrated solar light and an indium gallium nitride photocatalyst.

Bismuth vanadate (BiVO 4 ) has been widely investigated as a photocatalyst or photoanode for solar water splitting, but its activity is hindered by inefficient cocatalysts and limited understanding of the underlying mechanism. Here we demonstrate significantly enhanced water oxidation on the particulate BiVO 4 photocatalyst via in situ facet-selective photodeposition of dual-cocatalysts that exist separately as metallic Ir nanoparticles and nanocomposite of FeOOH and CoOOH (denoted as FeCoO x ), as revealed by advanced techniques. The mechanism of water oxidation promoted by the dual-cocatalysts is experimentally and theoretically unraveled, and mainly ascribed to the synergistic effect of the spatially separated dual-cocatalysts (Ir, FeCoO x ) on both interface charge separation and surface catalysis. Combined with the H 2 -evolving photocatalysts, we finally construct a Z-scheme overall water splitting system using [Fe(CN) 6 ] 3−/4− as the redox mediator, whose apparent quantum efficiency at 420 nm and solar-to-hydrogen conversion efficiency are optimized to be 12.3% and 0.6%, respectively. Artificial photosynthesis offers an integrated means to convert light to fuel, but efficiencies are often low. Here, authors report a Z-scheme system utilizing Ir and FeCoO x co-catalysts to enhance charge separation on BiVO 4 facets that achieves high quantum efficiencies for overall water splitting.

Bifunctional catalysts for hydrogen/oxygen evolution reactions (HER/OER) are urgently needed given the bright future of water splitting hydrogen production technology. Here, the self-supporting N and Ce dual-doped NiCoP nanoarrays (denoted N,Ce-NiCoP/NF) grown on Ni foam are successfully constructed. When the N,Ce-NiCoP/NF simultaneously acts as the HER and OER electrodes, the voltages of 1.54 and 2.14 V are obtained for driving 10 and 500 mA·cm −2 with a robust durability, and demonstrate its significant potential for practical water electrolysis. According to both experiments and calculations, the electronic structure of NiCoP may be significantly altered by strategically incorporating N and Ce into the lattice, which in turn optimizes the Gibbs free energy of HER/OER intermediates and speeds up the water splitting kinetics. Moreover, the sprout-shaped morphology significantly increases the exposure of active sites and facilitates charge/mass transfer, thereby augmenting catalyst performance. This study offers a potentially effective approach involving the regulation of anion and cation double doping, as well as architectural engineering, for the purpose of designing and optimizing innovative electrocatalysts.

Covalent organic frameworks (COFs) are an emerging type of crystalline and porous photocatalysts for hydrogen evolution, however, the overall water splitting activity of COFs is rarely known. In this work, we firstly realized overall water splitting activity of β -ketoamine COFs by systematically engineering N-sites, architecture, and morphology. By in situ incorporating sub-nanometer platinum (Pt) nanoparticles co-catalyst into the pores of COFs nanosheets, both Pt@TpBpy-NS and Pt@TpBpy-2-NS show visible-light-driven overall water splitting activity, with the optimal H 2 and O 2 evolution activities of 9.9 and 4.8 μmol in 5 h for Pt@TpBpy-NS, respectively, and a maximum solar-to-hydrogen efficiency of 0.23%. The crucial factors affecting the activity including N-sites position, nano morphology, and co-catalyst distribution were systematically explored. Further mechanism investigation reveals the tiny diversity of N sites in COFs that induces great differences in electron transfer as well as reaction potential barriers. Covalent organic frameworks (COFs) are an emerging type of crystalline and porous photocatalysts for hydrogen evolution. Here, the authors report a β-ketoamine COF by systematically engineering N-sites, architecture, and morphology for improved water splitting activity.