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[Display omitted] The pursuit of efficient and sustainable hydrogen production through water splitting has led to intensive research in the field of electrocatalysis. However, the impediment posed by sluggish reaction kinetics has served as a significant barrier. This challenge has inspired the development of electrocatalysts characterized by high activity, abundance in earth's resources, and long-term stability. In addressing this obstacle, it is imperative to meticulously fine-tune the structure, morphology, and electronic state of electrocatalysts. By systematically manipulating these key parameters, the full potential of electrocatalysts can unleash, enhancing their catalytic activity and overall performance. Hence in this study, a novel heterostructure is designed, showcasing core–shell architectures achieved by covering W 2 N-WC nanowire arrays with tri-metallic Nickel-Cobalt-Iron layered triple hydroxide nanosheets on carbon felt support (NiCoFe-LTH/W 2 N-WC/CF). By integrating the different virtue such as binder free electrode design, synergistic effect between different components, core–shell structural advantages, high exposed active sites, high electrical conductivity and heterostructure design, NiCoFe-LTH/W 2 N-WC/CF demonstrates striking catalytic performances under alkaline conditions. The substantiation of all the mentioned advantages has been validated through electrochemical data in this study. According to these results NiCoFe-LTH/W 2 N-WC/CF achieves a current density of 10 mA cm−2 needs overpotential values of 101 mV for HER and 206 mV for OER, respectively. Moreover, as a bi-functional electrocatalyst for overall water splitting, a two-electrode device needs a voltage of 1.543 V and 1.569 V to reach a current density of 10 mA cm−2 for alkaline water and alkaline seawater electrolysis, respectively. Briefly, this research with attempting to combination of different factors try to present a promising stride towards advancing bi-functional catalytic activity with tailored architectures for practical green hydrogen production via electrochemical water splitting process. [ABSTRACT FROM AUTHOR]

[Display omitted] • A Mn-doped nickel iron layered double hydroxides (Mn-doped NiFe-LDH) supported on nickel foam was developed, and could act as an efficient bifunctional catalyst for the coupling MOR and HER. • The methanol-to-formate faradaic efficiency was determined to be 99.5 % at an external potential of 1.5 V versus reversible hydrogen electrode. • This electrocatalyst is able to drive a current density of 131.1 mA cm−2 with a decay of merely 12.2 % over continuous 120 h testing in co-electrocatalysis of water/methanol solution. Electrochemical upgrading methanol into value-added formate at the anode in alkaline media enables the boosting production of hydrogen fuel at the cathode with saved energy. To achieve such a cost-effective and efficient electrocatalytic process, herein this work presents a Mn-doped nickel iron layered double hydroxides supported on nickel foam, derived from a simple hydrothermal synthesis. This developed electrocatalyst could act as an efficient bifunctional electrocatalyst for methanol-to-formate with a high faradaic efficiency of nearly 100 %, and for hydrogen evolution reaction, at an external potential of 1.5 V versus reversible hydrogen electrode. Additionally, a current density of 131.1 mA cm−2 with a decay of merely 12.2 % over 120 h continuous long-term testing was generated in co-electrocatalysis of water/methanol solution. Further density functional theoretical calculations were used to unravel the methanol-to-formate reaction mechanism arising from the doping of Fe and/or Mn. This work offers a good example of co-electrocatalysis to produce formate and green hydrogen fuel using a bifunctional electrocatalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing efficient and stable electrocatalysts at affordable costs is very important for large-scale production of green hydrogen. In this study, unique amphoteric metallic element-doped NiFe-LDH nanosheet arrays (NiFeCd-LDH, NiFeZn-LDH and NiFeAl-LDH) using as high-performance bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were reported, by tuning electronic structure and vacancy engineering. It was found that NiFeCd-LDH possesses the lowest overpotentials of 85 mV and 240 mV (at 10 mA cm−2) for HER and OER, respectively. Density functional theory (DFT) calculations reveal the synergistic effect of Cd vacancies and Cd doping on improving alkaline HER performance, which promote the achievement of excellent catalytic activity and ultrastable hydrogen production at a large current density of 1000 mA cm−2 within 250 h. Besides, the overall water splitting performance of the as-prepared NiFeCd-LDH requires only 1.580 V to achieve a current density of 10 mA cm−2 in alkaline seawater media, underscoring the importance of modifying the electronic properties of LDH for efficient overall water splitting in both alkaline water/seawater environments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Facile synthesis of structurally engineered Ternary Spinel-type NiFeCoO 4 nanoparticles. • Ni-Fe-Co elements work synergistically to enhance the electrocatalytic activity. • The defect engineered NiFeCoO 4 requires a low water splitting cell voltage of 1.67 V. Transition metal spinel oxides were engineered with active elements as bifunctional water splitting electrocatalysts to deliver superior intrinsic activity, stability, and improved conductivity to support green hydrogen production. In this study, we reported the ternary metal Ni-Fe-Co spinel oxide electrocatalysts prepared by defect engineering strategy with rich and deficient Na+ ions, termed NFCO-Na and NFCO, which suggest the formation of defects with Na+ forming tensile strain. The Na-rich NiFeCoO 4 spinel oxide reveals lattice expansion, resulting in the formation of a defective crystal structure, suggesting higher electrocatalytic active sites. The spherical NFCO-Na electrocatalysts exhibit lower OER and HER overpotentials of 248 mV and 153 mV at 10 mA cm−2 and smaller Tafel slope values of about 78 mV dec−1 and 129 mV dec−1, respectively. Notably, the bifunctional NFCO-Na electrocatalyst requires a minimum cell voltage of about 1.67 V to drive a current density of 10 mA cm−2. The present work highlights the significant electrochemical activity of defect-engineered ternary metal oxides, which can be further upgraded as highly active electrocatalysts for water splitting applications. [ABSTRACT FROM AUTHOR]

A hydrogen-bonded organic framework (HOF) nanowire was developed as a precursor and template for the synthesis of CoRu-MOF nanotubes and densely isolated CoRu alloy catalysts. The optimized Co-15Ru@NG-500 catalyst demonstrated superior catalytic performance for the HER in alkaline electrolytes with an overpotential of only 30 mV at 10 mA cm−2 and robust durability. [Display omitted] Designing highly efficient and stable electrocatalysts for hydrogen evolution reactions (HER) is essential to the production of green and renewable hydrogen. Metal-organic framework (MOF) precursor strategies are promising for the design of excellent electrocatalysts because of their porous architectures and adjustable compositions. In this study, a hydrogen-bonded organic framework (HOF) nanowire was developed as a precursor and template for the controllable and scalable synthesis of CoRu-MOF nanotubes. After calcination in Ar, the CoRu-MOF nanotubes were converted into N -doped graphene (NG) nanotubes with ultrafine CoRu nanoclusters (hereon called Co- x Ru@NG- T ; x = 0, 5, 10, 15, 25 representing the Ru content of 0–0.25 mmol; T = 400 °C to 700 °C) that were densely encapsulated and isolated on the shell. Taking advantage of the synergistic effects of the porous, one-dimensional hollow structure and ultrafine CoRu nanoclusters, the optimized Co-15Ru@NG-500 catalyst demonstrated superior catalytic performance for HERs in alkaline electrolytes with an overpotential of only 30 mV at 10 mA cm−2 and robust durability for 2000 cycles, which outperforms many typical catalytic materials, such as commercial Pt/C. This work introduces a novel high-efficiency and cost-effective HER catalyst for application in commercial water-splitting electrolysis. [ABSTRACT FROM AUTHOR]

A novel Fe, Co-CeO 2 /CeF 3 @MXene heterostructure with Fe-Co dual active sites and oxygen vacancies has been prepared for alkaline water/real seawater OER. [Display omitted] • Fe, Co-CeO 2 /CeF 3 @MXene heterostructure with Fe-Co dual active sites was synthesized by energy-free consumption co-deposition method. • Fe，Co-CeO 2 /CeF 3 @MXene can function as highly effective electrocatalyst toward OER. • The adsorption evolution mechanism and the lattice oxygen mechanism synergistically enhanced the OER activity. • Wind and solar-energy-assisted water electrolysis devices show their promising prospects for green hydrogen production sustainably. Exploring low-cost, high-activity, and structurally stable nonprecious metal electrocatalysts for sluggish oxygen evolution reaction (OER) is paramount for water electrolysis. Herein, we successfully prepare a novel Fe,Co-CeO 2 /CeF 3 @MXene heterostructure with Fe–Co dual active sites and oxygen vacancies for alkaline OER using an energy-free consumption co-deposition method. Impressively, Fe,Co-CeO 2 /CeF 3 @MXene achieves an ultralow overpotential of 192 mV and a long-term stability of 110 h at 10 mA cm−2 without structural changes, thereby outperforming the commercial IrO 2 (345 mV). In addition, Fe,Co-CeO 2 /CeF 3 @MXene exhibits much superior activity (271 mV) and durability to IrO 2 (385 mV) in the real seawater OER. Wind- and solar energy-assisted water electrolysis devices show their promising prospects for sustainable green hydrogen production. Characterization techniques and theoretical calculations reveal that the Fe,Co co-implanted CeO 2 /CeF 3 heterostructure effectively degrades the energy barrier of the OER and optimizes the adsorption strength of *OH, *O, and *OOH intermediates. It exhibits the dual coupling mechanism of the adsorbed evolution and lattice oxygen mechanisms, which synergistically improves the OER performance. This work provides a facile and efficacious strategy for synthesizing a new class of heterostructures to achieve significant enhancement in the activity and stability of OER catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanoneedle catalysts with core-shell structure were formed at room temperature. • CeO 2 adjusted and optimized the electronic structure of transition metal phosphides. • The catalysts exhibited excellent catalytic activities for both HER and OER. • The synthesized catalysts exhibited good structural stability. The discovery of earth-abundant electrocatalysts to replace platinum and iridium for overall water splitting is a crucial step in reducing the cost of green hydrogen production. Transition metal phosphides have drawn wide attention due to their non-toxicity, good chemical stability, low cost, and stable catalytic activity in alkaline electrolytes. We report a three-dimensional flower-like structure composed of core-shell nanoneedles as catalysts, in which CeO 2 is introduced on the surface of nickel cobalt bimetallic phosphide through electrodeposition. And X-ray photoelectron spectroscopy testing and DFT calculations show electron coupling and transfer between CeO 2 and CoP 3 , thereby modulating the electronic structure of the catalyst surface and reducing the adsorption energy of H atoms during the catalytic process, resulting in enhanced catalytic activity. In 1 M KOH, it exhibits a low overpotential of 109 and 296 mV to achieve the current density of 50 mA cm−2 for HER and OER, respectively. When used as both cathode and anode as a bifunctional catalyst, a voltage of only 1.77 V is required to achieve a current density of 50 mA cm−2, demonstrating great industrial potential. [ABSTRACT FROM AUTHOR]

The crystalline dependent discharge process shows strong structure-reforming ability on surface and promotes the formation of vacancies and thus reducing the adsorption energy of intermediate. [Display omitted] Alkaline water electrolysis is apreferred technology for large-scale green hydrogen production. For most active transition metal-based catalysts during anodic oxygen evolution reaction (OER), the atomic structure of the anodic catalysts' surface often undergoes reconstruction to optimize the reaction path and enhance their catalytic activity. The design and maintenance of highly active sites during this reconstruction process remain critical and challenging for most OER catalysts. In this study, we explored the effects of crystal structures in pre-catalysts on surface reconstruction at low applied potential. Through experimental observation and theoretical calculation, we found out that catalysts with specific crystal structures exhibit superior surface remodeling ability, which enables them to better adapt to the conditions of the oxygen evolution reaction and achieve efficient catalysis. The discharge process enables the formation of abundant phosphorus vacancies on the surface, which in turn affects the efficiency of the entire oxygen evolution reaction. The optimized crystal structure of the catalyst results in an increase as high as 58.5 mA/cm2 for Ni 5 P 4 , which is twice as high as that observed for Ni 2 P. These results provide essential theoretical foundations and technical guidance for designing more efficient catalysts for oxygen evolution reactions. [ABSTRACT FROM AUTHOR]

Schematic diagram representation the introduction of selenium and iron synergistically modulate the d-band center of Ni 3 S 2 to enhance oxygen evolution reaction (OER) and urea oxidation reaction (UOR). [Display omitted] • The introduction of selenium and iron synergistically modulated the d-band center of Ni 3 S 2 , resulting in the enhanced catalytic activity for the oxygen evolution reaction (OER) and urea oxidation reaction (UOR). • By adjusting the position of the d-band center, it is possible to optimize the adsorption and desorption energies of SeFe-Ni 3 S 2 towards urea molecules, as well as the overpotential for OER (η OER) and the limiting potential for UOR (U L). • The synthesized SeFe-Ni 3 S 2 presents as 3.9 nm lamellar structure with a larger specific surface area leading to the exposure of more active sites. Efficient production of green hydrogen energy is crucial in addressing the energy crisis and environmental concerns. The oxygen evolution reaction (OER) poses a challenge in conventional overall water electrolysis due to its slow thermodynamically process. Urea oxidation reaction (UOR) offers an alternative anodic oxidation method that is highly efficient and cost-effective, with favorable thermodynamics and sustainability. Recently, there has been limited research on bifunctional catalysts that exhibit excellent activity for both OER and UOR reactions. In this study, we developed a selenium and iron co-doped nickel sulfide (SeFe-Ni 3 S 2) catalyst that demonstrated excellent Tafel slopes of 53.9 mV dec−1 and 16.4 mV dec−1 for OER and UOR, respectively. Density Functional Theory (DFT) calculations revealed that the introduction of metal (iron) and nonmetallic elements (selenium) was found to coordinate the d-band center, resulting in improved adsorption/desorption energies of the catalysts and reduced the overpotentials and limiting potentials for OER and UOR, respectively. This activity enhancement can be attributed to the altered electronic coordination structure after the introduction of selenium (Se) and iron (Fe), leading to an increase in the intrinsic activity of the catalyst. This work offers a new strategy for bifunctional catalysts for OER and UOR, presenting new possibilities for the future development of hydrogen production and novel energy conversion technologies. It contributes towards the urgent search for technologies that efficiently produce green hydrogen energy, providing potential solutions to mitigate the energy crisis and protect the environment. [ABSTRACT FROM AUTHOR]

A high dispersed 2D NiFeP/CoP heterogeneous catalyst was designed and constructed by in situ transformation from nanorod CoO for catalyzing oxygen evolution reaction, urea oxidation reaction, and hydrogen evolution reaction. [Display omitted] The electrocatalytic production of "green hydrogen", such as through the electrolysis of water or urea has been vigorously advocated to alleviate the energy crisis. However, their electrode reactions including oxygen evolution reaction (OER), urea oxidation reaction (UOR), and hydrogen evolution reaction (HER) all suffer from sluggish kinetics, which urgently need catalysts to accelerate the processes. Herein, we design and prepare an OER/UOR/HER trifunctional catalyst by transforming the homemade CoO nanorod into a two-dimensional (2D) ultrathin heterojunction nickel–iron-cobalt hybrid phosphides nanosheet (NiFeP/CoP) via a hydrothermal-phosphorization method. Consequently, a strong electronic interaction was found among the Ni 2 P/FeP 4 /CoP heterogeneous interfaces, which regulates the electronic structure. Besides the high mass transfer property of 2D nanosheet, Ni 2 P/FeP 4 /CoP displays improved OER/UOR/HER performance. At 10 mA cm−2, the OER overpotential reaches 274 mV in 1.0 M KOH, and the potential of UOR is only 1.389 V in 1.0 M KOH and 0.33 M urea. More strikingly, the two-electrode systems for electrolysis water and urea-assisted electrolysis water assembled by NiFeP/CoP could maintain long-term stability for 35 h and 12 h, respectively. This work may help to pave the way for upcoming research horizons of multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

The decarbonization of the energy sector has been a subject of research and of political discussions for several decades, gaining significant attention in the last years. It is commonly acknowledged that the most obvious way to achieve decarbonization is the use of renewable energy sources. Within the context of the energy sector decarbonization, many mainly industrialized countries recently started developing national plans to establish a hydrogen-based economy in the very near future. The plans for green hydrogen initially try to (a) target sectors that are difficult to decarbonize and (b) address issues related to the storage and transportation of CO 2 -free energy. To achieve almost complete decarbonization, electric power must be generated exclusively from renewable sources. In so-called Power-to-X (PtX) technologies, green hydrogen is generated from electricity and subsequently converted to another energy carrier which can be further stored, transported and used. In PtX, X stands, for example, for liquid hydrogen, methanol or ammonia. The challenges associated with decarbonization include those associated with (a) the expansion of renewable energies (e.g., high capital demand, political and social issues), (b) the production, transportation, and storage of hydrogen and the energy carriers denoted by X in PtX (e.g., high cost and low overall efficiency), and (c) the expected significant increase in the demand for electrical energy. The paper discusses whether and under which conditions the current national and international hydrogen plans of many industrialized countries could lead to a maximization of decarbonization in the world. It concludes that, in general, as long as the conditions for generating large excess amounts of green electricity are not met, the quick establishment of a hydrogen economy could not only be very expensive, but also counterproductive to the worldwide decarbonization efforts. • The paper addresses the decarbonization of the energy sector. • Use of hydrogen in the very near future does not promote decarbonization. • Power-to-X technologies are inefficient and very costly. • Currently we must focus on the expansion of green electricity. [ABSTRACT FROM AUTHOR]

The large-scale application of hydrogen steelmaking technology is expected to substantially accelerate the decarbonization process of the iron and steel industry. However, hydrogen steelmaking projects are still in the experimental or demonstration stage, and scientific investment decision-making methods are urgently needed to support the large-scale development of the technology. When assessing the investment value, existing studies usually only consider the intrinsic project value under a specific pathway, while ignoring the option value under realistic multiple uncertainties in terms of technology, market, and policy, leading to an underestimation of the investment value. To address this issue, this study constructs a real options model to explore the optimal investment timing and revenue of the hydrogen steelmaking project, by taking into account multi-dimensional uncertainties stemming from price fluctuations in the steel market, the development of the carbon market, and technological advances. Additionally, the impacts of various subsidy policies on the investment strategy are also investigated. Least Squares Monte Carlo method is applied to overcome computational challenges posed by dynamic programming under multi-dimensional uncertainties. The results show that: (i) Investment is not recommended based on current crude steel price and hydrogen price. (ii) When the annual reduction rate of hydrogen price reaches 5%, the optimal investment timing would advance to 2036. (iii) On this basis, with the introduction of a 20% green hydrogen subsidy policy, the optimal investment timing would be further brought forward to 2033. The implementation of tax incentives would significantly increase the investment value. The investment value would surge from 170 million CNY to 262 million CNY as the tax rate decreases from 20% to zero. The findings could provide reasonable suggestions for investment decisions under realistic volatile environments, as well as scientific references for policy design, thus facilitating the large-scale and high-level development of hydrogen-based steelmaking technology. • Considering multiple uncertainties in hydrogen steelmaking project decision making. • Building Real Option Model for investment strategy of hydrogen steelmaking project. • Best time to invest is 2036 at 5% decline rate of H 2 price and current steel price. • Analyzing incentive effects of one-time subsidy, H 2 incentives and tax incentives. • Subsidy for H 2 is the most effective incentive to advance the investment timing. [ABSTRACT FROM AUTHOR]

Globally waste incineration is becoming the predominant treatment method of solid waste. The largest fraction of solid residue of this process is incineration bottom ash (IBA) requiring further treatment before applications such as in the construction industry become feasible. In this study, vitrification of IBA was conducted in a demonstration-scale high-temperature slagging gasification plant fueled with MSW and biomass charcoal as a green auxiliary fuel. High IBA co-feeding rates of up to 491 kg/h (equivalent to 107% of MSW feeding rate) were achieved during the trials. A highly leaching-resistant slag immobilizing heavy metals in the glass-like amorphous structure and recyclable iron-rich metal granules were generated in the process. The heavy metal migration into the solid by-product fractions depended on the IBA feeding rates and process conditions such as cold cap temperature, charcoal-to-ash ratio, and gasifier temperature profile. Slaked lime and activated carbon powder were used in a dry flue gas treatment and stack gas emissions were kept well below Singapore's regulatory limits. Steam from the hot flue gas was generated in a boiler to drive a steam turbine. The application of biomass charcoal instead of fossil fuels or electricity lead to a lower carbon footprint compared to alternative vitrification technologies. The overall results reveal promising application of high temperature slagging gasification process for commercial-scale vitrification of IBA. [Display omitted] • Demonstration-scale treatment of incineration bottom ash in slagging gasifier. • Converted incineration bottom ash into high quality and leaching resistant slag. • Investigated metal migration into solid residues depending on operation conditions. • Maintained stable gasifier operation and kept emissions below regulatory limits. • Lower carbon footprint in slagging gasification versus coke and electric melting. [ABSTRACT FROM AUTHOR]

Given the dire state of climate change, investigating key elements that impact the energy transition process and help monitor progress in greenhouse gas emissions to achieve environmental sustainability is of critical importance. The current study explores the association between energy transition, compliance with environmental agreements, fossil fuels costs, environmental technologies, economic growth, and environmental degradation in G20 economies from 1995 to 2019. Our findings from extensive econometric analysis reveal that economic growth, environmental innovation, renewable energy, and environmental compliance facilitate while fossil fuels and environmental degradation hinder the energy transition process. Our findings conclude that developed countries must focus on alternate energy resources to overcome environmental challenges and subsidize renewable energy and environmental technologies to replace fossil fuels with green energy resources methodologically. Further, policy measures have been discussed in detail in the study. • Climate change has resulted in dramatic shifts in environmental policymaking. • We evaluate the role of energy innovation, fossil fuel costs and environmental compliance towards Energy Transition. • We need to focus on alternate energy resource and replace fossil fuels with green energy resources. [ABSTRACT FROM AUTHOR]

[Display omitted] • The multinuclear Fe5 complex is highly active in electrocatalytic water oxidation. • Advanced in situ spectroscopic studies identify reactive intermediates of Fe5 cluster. • FeIV/ FeV oxidation states and Fe = O bond ∼ 1.6 Å are present during water oxidation. • Fe O forms by expansion at 5-coordinate Fe with coordination of 6th water ligand. • Fe5-MIL-126 MOF composite is photoelectrocatalytic for water oxidation. Photoelectrochemical water splitting can produce green hydrogen for industrial use and CO 2 -neutral transportation, ensuring the transition from fossil fuels to green, renewable energy sources. The iron-based electrocatalyst [FeII 4 FeIII(μ-3-O)(μ- L) 6 ]3+ (L H = 3,5-bis(2-pyridyl)pyrazole) (1) , discovered in 2016, is one of the fastest molecular water oxidation catalysts (WOC) based on earth-abundant elements. However, its water oxidation reaction (WOR) mechanism has not been yet fully elucidated. Here, we present in situ X-ray spectroscopy and electron paramagnetic resonance (EPR) analysis of electrochemical WOR promoted by (1) in water-acetonitrile solution. We observed transient reactive intermediates during the in situ electrochemical WOR, consistent with a coordination sphere expansion prior to the onset of catalytic current. At a pre-catalytic (∼+1.1 V vs. Ag/AgCl) potential, the distinct g ∼ 2.0 EPR signal assigned to FeIII/FeIV interaction was observed. Prolonged bulk electrolysis at catalytic (∼+1.6 V vs. Ag/AgCl) potential leads to the further oxidation of Fe centers in (1). At the steady state achieved with such electrolysis, the formation of hypervalent FeV O and FeIV O catalytic intermediates was inferred with XANES and EXAFS fitting, detecting a short Fe O bond at ∼ 1.6 Å. (1) was embedded into MIL-126 MOF with the formation of a (1) -MIL-126 composite. The latter was tested in photoelectrochemical WOR and demonstrated an increase in electrocatalytic current upon visible light irradiation in acidic (pH = 2) water solution. The presented spectroscopic analysis gives further insight into the catalytic pathways of multinuclear systems and should help the subsequent development of more energy- and cost-effective water-splitting catalysts based on earth-abundant metals. Photoelectrocatalytic activity of (1) -MIL-126 confirms the possibility of creating an assembly of (1) inside a solid support and harnessing solar irradiation towards industrial applications of the catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of effective photocatalyts for H 2 generation. • Alternative and sustainable renewable energy sources. • Synergism between Ag 2 S/Cu 2 S co-catalysts on CdZnS. • Replacement of costly catalysts with cheaper options. • Environmental friendly and green fuel production approach. Photocatalytic hydrogen production through water splitting is one of the effective ways to fulfill future energy demands. In current study, Ag and Cu were simultaneously incorporated into CdZnS through hydrothermal reaction to synthesize 1 % Ag 2 S/Cu 2 S codoped-CdZnS. The catalysts were characterized via XRD, FT-IR, SEM, EDX, UV–Vis/DRS, XPS, BET, PL and EIS techniques. It has been observed that 1 % Ag 2 S/Cu 2 S is optimized amount of dopants that enables CdZnS to produce hydrogen with 9.76 mmol g−1h−1 rate. This amount of H 2 is 3 times higher than that of bare CdZnS (2.91 mmol g−1h−1). Photocatalytic activity shown by 1 % Ag 2 S/Cu 2 S-CdZnS is due the incorporation of Ag and Cu which exist in the form of Ag 2 S and Cu 2 S clusters respectively and causes synergistic effect during photoreaction. During the photoreactions, oxidation half reactions occur at Ag 2 S, while reduction half reaction at Cu 2 S (i.e. conversion of H+ ions to H 2). On the basis of the results, it can be concluded that Cu 2 S acts as reduction co-catalyst while Ag 2 S serves as oxidation co-catalyst in water reduction reaction. This work could offer efficient and low cost photocatalysts for hydrogen production from the water splitting reactions. [ABSTRACT FROM AUTHOR]

Photocatalysis is considered as an eco-friendly and sustainable strategy, since it uses abundant light for the advancement of the reaction, which is freely accessible and is devoid of environmental pollution. During the last decades, (nano)photocatalysts have gained broad industrial applications in terms of purification and detoxification of water as well as production of green fuels and hydrogen gas due to their special attributes. The degradation or remediation of toxic and hazardous compounds from the environment or changing them into non-toxic entities is a significant endeavor and necessary for the safety of humans, animals, and the environment. Black phosphorus (BP), a two-dimensional single-element material, has a marvelous structure, tunable bandgap, changeable morphology from bulk to nanosheet/quantum dot, and unique physicochemical properties, which makes it attractive material for photocatalytic applications, especially for sustainable development purposes. Since it can serve as a photocatalyst with or without coupling with other semiconductors, various aspects for multidimensional exploitation of BP are deliberated including their preparation via solvothermal, ball milling, calcination, and sonication methods to obtain BP from red phosphorus. The techniques for improving the photocatalytic and stability of BP-based composites are discussed along with their multifaceted applications for environmental remediation, pollution degradation, water splitting, N 2 fixation, CO 2 reduction, bacterial disinfection, H 2 generation, and photodynamic therapy. Herein, most recent advancements pertaining to the photocatalytic applications of BP-based photocatalyst are cogitated, with a focus on their synthesis and properties as well as crucial challenges and future perspectives. [Display omitted] • Significant advances in the development of black phosphorus-based photocatalysts are reviewed. • The synthesis and applications of phosphorus-based compounds are summarized. • Environmental and biomedical applications of have been discussed. [ABSTRACT FROM AUTHOR]