Cooperative photocatalysis for simultaneous hydrogen peroxide (H2O2) production and organic oxidation presents a sustainable approach to solar-to-chemical energy conversion. While ZnxIn2Sx+3 materials are promising candidates, the study of high stoichiometry (x > 1) variants is still limited. Moreover, the synergy of mixed-phase C3N5 and ZnxIn2Sx+3 remains to be explored. Herein, a series of ZnxIn2Sx+3 (x = 1–4) photocatalysts (RZISx) were synthesized via reflux, with Zn3In2S6 (x = 3) identified as the optimal composition, achieving H2O2 and benzaldehyde production rates of 1430.9±65.6 μM h−1 and 2473.2±264.2 μM h−1, respectively. Crystalline C3N5 (CCN550) was synthesized by the molten-salt method and a ternary heterostructure (5CCN/RZIS3) was further developed by compositing Zn3In2S6 with CCN550 during refluxing, leading to enhanced yields of H2O2 (2655.2±167.1 μM h−1; apparent quantum efficiency (AQE): 1.1% at 420 nm) and benzaldehyde (2685.9±126.5 μM h−1). Improved performance stems from the intimate interface between Zn3In2S6 and heptazine/triazine domains in C3N5, which facilitates efficient charge separation and boosts O2 adsorption. Rotating disk electrode measurements confirmed high selectivity toward the two-electron oxygen reduction pathway. This study introduces a ternary heterojunction strategy and provides insights into the role of crystalline structure and heterointerface engineering in advancing dual-functional photocatalysis.

For a clean and sustainable society, there is an urgent demand for renewable energy with net-zero emissions due to fossil fuels limited resources and irreversible environmental impact. Hydrogen has the unrivaled potential to replace fossil fuels due to its high gravimetric energy density, abundant sources (H 2 O), and environmental friendliness. However, its low volumetric energy density causes significant challenges, inspiring major efforts to develop chemical-based storage alternatives. Solid-state hydrogen storage in materials has substantial potential for fulfilling the practical requirements and is recognized as a potential candidate due to their properties tuning more independently. However, hydrogen's stable thermodynamics and sluggish kinetics are the bottleneck to its widespread applications. To explore the kinetic and thermodynamic barriers in the fundamentals of hydrogen storage materials, this review will provide promising information for researchers to gain detailed knowledge about hydrogen storage energy applications and find new routes for materials engineering with tuned properties. This will further attract a wider scientific community and intend to understand the innovative concepts and strategies developed and to employ them in tailoring hydrogen storage materials' kinetic and thermodynamic properties. Recent advances in nanostructuring, nanoconfinement with in situ catalysts, and host/guest stress/strain engineering have the potential to propel the prospects of tailoring the hydrogen storage materials properties at the nanoscale with several promising directions and strategies that could lead to the next generation of solid-state hydrogen storage practical applications.

In the context of addressing global energy demands, microwave plasma-assisted methane pyrolysis emerges as a promising method for controlled and energy-efficient decomposition of methane. This electrode-less, substrate-less, and catalyst-free one-step process of microwave plasma plays a pivotal role in the synthesis of few-layer graphene (FLG) with no greenhouse gases as byproducts. In this work, the experimental setup features a commercial microwave plasma torch operating at 2.45 GHz with a microwave power starting from 1 kW, employing argon as a carrier gas. Optical emission spectroscopy was used to analyze the plasma species. Raman spectroscopy, transmission electron microscopy, atomic force microscopy, and Brunauer-Emmett-Teller surface area analysis were used to characterize the synthesized graphene. Numerical simulations using ZDPlasKin and Cantera software facilitated the understanding of plasma thermochemistry and reaction kinetics due to microwave plasma gas heating. Parametric studies were performed to investigate the effect of parameters such as the gas mixture ratio, gas flow rate, and microwave power on the plasma and the synthesized graphene. With a high temperature range from 2500 to 4500 K, growth of pristine graphene is influenced by the acetylene (C2H2) formed by the dehydrogenation process. Results indicate that a 9/1 gas ratio Ar/CH4 gas mixture ratio optimizes methane conversion and promotes the formation of key species such as C2H2, essential for quality FLG synthesis. The best graphene quality was achieved at 1.5 kW power with Raman spectra showing a high I 2D/I G ratio of 1.05 and a low I D/I G ratio of 0.36, indicating FLG with minimal defects. The study reveals a significant effect of plasma gas temperature on the dehydrogenation process of C2H2, which in turn affects the quality of the synthesized graphene.

This study constructed a synergistic homo-/heterojunction zinc blende/wurtzite cadmium sulfide/phosphorus-doped polymeric C3N5 (ZB/WZ CS/PCN). It was found that manipulating Cd/S precursor ratio with Na2S as the S precursor can effectively control the growth of high-energy facets. Concurrently, the presence of P-doping in PCN can adequately tune the optical properties of CN through the presence of P-C/P-N/PN linkage within the CN heterocyclic ring. Owing to the intimate heterojunction which boosted the carrier transfer between CS and PCN, the optimal CS/PCN 10% produced 3840.5 mu mol g(-1) h(-1) of hydrogen with prolonged stability (>56 h), giving rise to the intimate heterojunction and robustness. As a proof-of-concept, CS/PCN 10% was also deposited onto a 3D printed substrate obtained by fused deposition modeling (FDM), offering clear advantages for reusability of light-induced photocatalytic applications. Overall, this work provides insights into the universal application of CS/PCN photocatalysts in future scale-up opportunities of photocatalytic-based systems.

The artificial recycling of CO2 into value-added feedstocks and chemicals provides a sustainable approach to mitigate its greenhouse effect and realize a carbon-neutral economy, for which the direct and efficient utilization of CO2 reduction products without additional separation and purification remains challenging. Here an electrochemical-biological hybrid system has been developed to merge CO2 electrolysis with municipal wastewater treatment. In this set-up, the formate produced electrocatalytically (formate-e) in neutral electrolyte (1.0 M KHCO3) is directly applied as a carbon source and energy carrier for biological denitrification using activated sludge from municipal wastewater treatment plants, exhibiting an excellent nitrate nitrogen (NO3--N) removal rate of similar to 3.06 mg l(-1) h(-1). Moreover, after long-term continuous operation of the tailored denitrification bioreactor, the formate-e displayed high denitrification rate of 1.08 mgNO(3)(-)-N per gram suspended solids per litre per hour, surpassing that of acetate, widely used as a commercial carbon source. Further environmental and techno-economic analyses suggest that integrating this electrochemical-biological hybrid system with an electrochemical recovery and separation system can significantly lower the cost of the electrolyte, thereby showing promise for the direct use of formate-e in industrial applications for wastewater treatment.

A global model on microwave Ar/CH4/H2 plasma is developed. The number density of C, C2 and C2H2 at low pressure, reduced pressure and atmospheric pressure are compared. Atmospheric pressure is favorable for graphene growth, and our simulation shows that high C2/C and C2H2/C ratios are achieved under this condition. Ratio analysis incorporating C2/C, C2H2/C and C2H2/C2 and selectivity analysis are introduced for conducting parametric studies including microwave power (200 to 600 W), flow rate (1 to 5 slm), CH4 percentage (1 to 35 %) and H2 percentage (1 to 30 %) systematically. C2/C, C2H2/C, and C2H2/C2 ratios decrease with increasing microwave power; 200 W is chosen ideal microwave power. High selectivity of C, C2, and C2H2 is observed at 400 W, corresponding to a gas temperature of 3000 K. A flow rate of 5 slm ensures sufficient residence time for sp² growth, as indicated by elevated C2/C and C2H2/C ratios. The analysis shows that while higher CH4 levels enhance C2/C, C2H2/C, and C2H2/C2 ratios, the sharp decline in the selectivity of C, C2, and C2H2 increases the risk of amorphous carbon. The analysis indicates that 10 % H2 offers balanced C2/C, C2H2/C, and C2H2/C2 ratios while 1 to 10 % H2 achieves the highest C2H2 selectivity. Experimental validation confirmed 2 to 5 % H2 and 16 to 22 % CH4 as optimal, which is in agreement with simulated values. As such, this work casts a robust framework for optimizing reactor design and operation through ratio and selectivity analyses, enabling efficient and scalable graphene production.

In a world striving for sustainable energy, advanced electrocatalysts are pivotal to enabling efficient chemical transformations with minimal energy costs. Herein, we uncover a practical approach for the simultaneous electrochemical CO2 reduction (CO2RR) and alcohol oxidation (AOR), enabling the selective valuable chemicals production. Central to this innovation is a self-supported electrocatalyst, featuring sulfur-enhanced CuBi2O4 nanospheres anchored on NrGO nanosheets (SCB/NG), achieved a faradaic efficiency for C2+ products (FEC2+) exceeding 92.4% over 200 h, while demonstrating near-total selectivity for benzaldehyde and >83% for furfural. Beyond that, in situ Raman spectroscopy and DFT calculations reveal *CO dimerization and the key intermediates coverage, providing deep mechanistic insights into the reaction pathway. Additionally, by being integrated into a solar-powered platform, the bifunctional system achieves a solar-to-fuel conversion efficiency of 16% with over 98% retention, offering a scalable strategy for coupling CO2 utilization with high-value chemical production and paving the way toward energy-efficient, carbon-neutral technologies.

Catalytic urea-assisted hydrogen production represents an awe-inspiring breakthrough, advancing sustainable global energy security and environmental remediation. Herein, an innovative self-supported heterostructure electrocatalyst, NiSe2/Ni3Se4@NiCoFe-LDH/NF, is fabricated via a facile hydrothermal-selenization-electrodeposition method for bifunctional HER and UOR. The integration of 2D LDH nanosheets with 2D dual-phased nickel selenides enhances active site density, structural lustiness and charge/mass transport, sustaining performance for over 60 h at high current density (100 mA cm-2) and achieving high Faradaic efficiencies of 98.90% for HER and 90.97% for UOR. The NSLDH-0.7/NF exhibits low overpotential (potential) of 110 mV versus RHE (1.295 V versus RHE) to attain a current density of 10 mA cm-2 in alkaline media, with ultralow Tafel slope of 13.23 mV dec-1 (21.98 mV dec-1) in catalyzing HER (UOR), which is comparatively lower compared to the reported values in literature. The in situ Raman investigation highlights NiOOH as the stable active site responsible for catalyzing urea oxidation, effectively linking catalyst reconstruction to its electrochemical performance. This work demonstrates the practical viability of this appealing electrocatalyst in a two-electrode urea electrocatalytic cell, while offering novel insight into the rational design of efficient electrocatalysts for simultaneous wastewater purification and sustainable hydrogen production.

Recently, solar steam generation (SSG) has emerged as a promising and sustainable technology for addressing global water scarcity by efficiently converting solar energy to produce clean water. Carbonaceous materials, primarily sourced from biomass-based, have attracted significant attention due to their sustainable use of natural resources. However, biomass-based materials are easily mildewed during prolonged immersion and the carbonization process can significantly alter the natural hydrophilic properties of biomass. Herein, a novel approach that utilizes the integration of zinc oxide (ZnO) on carbonized oil palm fiber (ZnO-CF) is developed in this study to investigate their combined synergistic effect. Through a cost-effective hydrothermal route, a composite photothermal material with efficient light absorption and water transport properties is successfully synthesized. Benefiting from the synergistic effect of ZnO with CF, the evaporation rate and efficiency of ZnO-CF are reported to be 1.739 kg m-2h- 1 and 98.96 %, respectively, under 1 sun illumination. Additionally, ZnO-CF demonstrated excellent desalination and bactericidal properties in treating lake water and seawater, with the additional feature of merit in sustaining self-cleaning ability for crystalline salt due to its surface wettability in the absence of light. These versatile properties make ZnO-CF a favorable solution for biomass waste upcycling from the oil palm industry, thus contributing to sustainable water desalination technologies.

This protocol presents both the synthesis of the visible-light-responsive ZnCoS/ZnCdS with twin crystal structure photocatalyst and the photoredox reaction testing of its photocatalytic activity and selectivity in H2 evolution and benzaldehyde production. This ZnCoS/ZnCdS heterostructure integrates the mixed-phase junction advantage of ZnCdS semiconductor and the cocatalytic function of ZnCoS acting as an electron reservoir to facilitate the surface reaction. Notably, the existence of twin crystal structure within a ZnCdS semiconductor purportedly presents a nano-scaled twin superlattice configuration with an alternative arrangement of long-range-ordered twinned planes, which gives rise to a unique wurtzite/zinc blende (WZ/ZB) interphase junction. This interphase junction possesses an interfacial electrostatic field, resulting in excellent photoexcited charge carrier separation and transport to the specimen surface, hence facilitating redox reactions. We report a facile hydrothermal approach to prepare the visible-light-responsive ZnCoS/ZnCdS with twin crystal structure, where the ZnCoS plays a crucial role in capturing photoinduced electrons on the catalyst surface. UV-Vis diffuse reflectance spectroscopy and N2 physisorption measurement were conducted to determine the photoabsorption ability and surface area of the sample, respectively. A detailed setup of solar-driven H2 production coupled with benzyl alcohol oxidation and an online gas chromatography was demonstrated. The ZnCoS/ZnCdS exhibited an enormous enhancement in both H2 and benzaldehyde formation. The correlation between ZnCoS co-catalyst and WZ/ZB phase junctions of ZnCdS towards the photocatalytic behavior was systematically assessed. This casts a novel idea to optimize the design of dual-functional photocatalysts for multifarious energy applications.

Despite advances in photocatalytic half-reduction reactions, challenges remain in effectively utilizing electron-hole pairs in concurrent redox processes. The present study involved the construction of a p-n junction Co3O4/Zn3In2S6 (CoZ) hybrid with a complementary band edge potential. The photocatalyst formed by the 2D assembled-nanostructure portrayed an optimal yield of 13.8 (H-2) and 13.1 (benzaldehyde) mmol g(-1) h(-1) when exposed to light (lambda > 420 nm), surpassing 1 % Pt-added ZIS (12.4 (H-2) and 10.71 (benzaldehyde) mmol g(-1) h(-1)). Around 95 % of the electron-hole utilization rate was achieved. The solar-to-hydrogen (STH) and apparent quantum yield (AQY) values of 0.466 % and 4.96 % (420 nm) achieved by this system in the absence of sacrificial agents exceeded those of previous works. The exceptional performance was mostly ascribed to the synergistic development of adjoining p-n heterojunctions and the built-in electric field for effective charge separation. Moreover, scavenger studies elucidated the intricate mechanistic enigma of the dual-redox process, in which benzaldehyde was produced via O-H activation and subsequent C-H cleavage of benzyl alcohol over CoZ hybrids. Furthermore, the widespread use of the optimal 1-CoZ composites was confirmed in multiple photoredox systems. This work presents an innovative perspective on the construction of dual-functioning p-n heterojunctions for practical photoredox applications.

Amid the ongoing transition toward renewable fuels, the self-supported layered double hydroxides (LDHs) are envisioned as propitious electrocatalysts for reinvigorating the electrocatalysis realm, thereby facilitating environmental remediation and bolstering sustainable global energy security. Exploiting appealing attributes such as unique lamellar structure, abundant active sites, tunable intercalation spacing and compositional flexibility, LDHs boast remarkable activity, selectivity and stability across diverse energy-related applications. By virtue of addressing the technological and time prominence of excavating their renaissance, this review first encompasses the facile state-of-the-art synthetic approaches alongside intriguing modification strategies, toward deciphering the authentic structure–performance correlations for advancing more robust and precise catalyst design. Aside from this, heterostructure engineering employing diversified ranges of coupling materials is highlighted, to construct ground-breaking binder-free LDHs-based heterostructures endowing with unprecedented activity and stability. Subsequently, the milestone gained from experimental research and theoretical modeling of this frontier in multifarious electrocatalytic applications, including HER, OER, UOR, AOR, seawater splitting and other fundamental conversion reactions is rigorously unveiled. As a final note, a brief conclusion is presented with an outline of future prospects. Essentially, this review aspires to offer enlightenment and incite wise inspiration for the future evolution of innovative and resilient next-generation catalysts.

Advancement in photocatalysts is essential for improving their feasibility. This can be achieved by eliminating the need for sacrificial agents in conventional half-reactions. Additionally, co-producing two products via the redox reaction allows for the full utilization of electron-hole pairs in photocatalysis. Herein, a carbon nitride heptazine/triazine homojunction was synthesized via eutectic salt-assisted one-step ionothermal polymerization for the simultaneous photoreduction of O2 into H2O2 and selective photooxidation benzyl alcohol (BA) into benzaldehyde (BAD). The optimal CCN-550 demonstrated robust photocatalytic performances with yields of 5838.91 and 7041.32 mu mol L-1h- 1 for H2O2 and BAD simultaneously with 100 % selectivity, recording 31.7 and 14.5-fold higher compared to the pristine structure, respectively with an apparent quantum yield of 11.57 % (420 nm). The photoredox reaction mechanism was unveiled as a sequential two-step single electron transfer process, attested by the 1.38 electron transfer from rotating disk electrode (RDE), radical quenching test and electron paramagnetic resonance. The bolstered catalytic performance is attributed to the PHI/PTI homojunction and the synergistic effect from the homojunction owing to intercalated K+ for instantaneous charge transmission and the formation of cyano group serving as the electron traps.

In the quest to address the escalating plastic pollution, artificial photosynthesis offers an innovative approach to upcycling plastic waste into clean fuels and valuable chemicals. However, arduous challenges remain in the realm of photocatalysis due to the inefficient utilization of electron‐hole pairs. In this work, a n‐p heterojunction Cd 2 In 2 S 5 /Co 3 O 4 composite with a built‐in electric field is engineered to convert an omnipresent plastic, namely polyethylene terephthalate (PET), into H 2 (63.10 µmol h −1 ) and organic chemicals (formic acid: 8.34 µmol h −1 ; oxalic acid: 1.22 µmol h −1 ; glycolic acid: 5.22 µmol h −1 ) under the visible light irradiation. The solar‐to‐hydrogen and apparent quantum efficiency in this sacrificial‐substrate‐free system achieve a value of 0.17% and 0.48% (420 nm), respectively. The excellent performance is primarily accredited to the expanded light absorption range, enhanced specific surface area, improved carrier separation efficiency, and boosted interfacial charge transport. Advanced characterization techniques, including KPFM and EPR, uncover the intricate charge transfer dynamics of PET photoreforming, where the photogenerated holes accumulated on Co 3 O 4 initiate the plastic oxidation half‐reaction. Finally, the photoreforming of real‐world PET bottles demonstrates the broad universality of Cd 2 In 2 S 5 /Co 3 O 4 hybrids. This research presents a trailblazing standpoint for the design of p‐n heterojunctions to bridge new exemplifications toward environmental sustainability.

The design of highly efficient photocatalysts to photoreduce nitrogen (N 2 ) to ammonia (NH 3 ) under mild conditions is extremely challenging. In this work, various molar ratio of molybdenum (Mo) is incorporated into Bi 12 O 17 Cl 2 via a hydrothermal process. The resulting Mo‐doped Bi 12 O 17 Cl 2 exhibits remarkable solar‐driven activity for N 2 photo fixation without any scavengers or sacrificial agents. The optimal sample with 5% Mo dopants displays an NH 3 yield of 39.83 µmol g −1 h −1 , a 1.6‐fold improvement over undoped pristine Bi 12 O 17 Cl 2 . The impressive performance is attributed to the synergistic effects of oxygen vacancies (OVs) and Mo‐loading, enhancing light absorption and extending photo‐response through band gap reduction. Additional contributions arise from the enriched active sites, facilitating N 2 adsorption and electron transport to the reactants. Density functional theory calculations reveal that Mo integration induces significant charge redistribution around the active sites, thereby reducing the energy barrier associated with N 2 activation and protonation. In‐depth investigation into the reaction pathway unravels the step‐by‐step reaction process which further elucidates the beneficial role of Mo loading in the overall N 2 photoconversion process. As a whole, this work promotes a simple and effective engineering approach based on heteroatom doping as an efficacious strategy to design highly active photocatalysts toward N 2 photo fixation.

Homojunction engineering is a promising modification strategy to improve charge carrier separation and photocatalytic performance of carbon nitrides. Leveraging intrinsic heptazine/triazine phase and face-to-face contact, crystalline C3N5 (CC3N5) was combined with protonated g-C3N4 (pgCN) through electrostatic self-assembly to achieve robust 2D/2D homojunction interfaces. The highest photocatalytic performance was obtained through crystallinity and homojunction engineering, by controlling the pgCN:CC3N5 ratio. The 25:100 pgCN:CC3N5 homojunction (25CgCN) had the highest hydrogen production (1409.51 μmol h−1) and apparent quantum efficiency (25.04%, 420 nm), 8-fold and 180-fold higher than CC3N5 and pgCN, respectively. This photocatalytic homojunction improves benzaldehyde and hydrogen production activity, retaining 89% performance after 3 cycles (12 h) on a 3D-printed substrate. Electron paramagnetic resonance demonstrated higher ·OH−, ·O2− and hole production of irradiated 25CgCN, attributed to crystallinity and homojunction interaction. Thus, electrostatic self-assembly to couple CC3N5 and pgCN in a 2D/2D homojunction interface ameliorates the performance of multifunctional solar-driven applications.

Dual-functional photocatalytic oxygen reduction reaction and benzyl alcohol oxidation represent a clean and sustainable strategy for cooperative chemical synthesis. In this study, carbon-doped crystalline C3N5 (C-CCN) was developed via a molten-salt-assisted liquid-phase recrystallization and polymerization approach. The photocatalytic activity of optimal C-CCN0.7 attained 564.81 and 595.37 mu M h-1 for H2O2 and benzaldehyde coproduction, respectively, with electron-hole utilization rate of 95 %, stemming from improved HOMO-LUMO delocalization around the C-H functional group. Experimental analysis and density functional theory demonstrate that the N atoms in the terminal NH/NH2 amino groups were substituted by C atoms, creating CH/CH2 functional groups on the dangling ends of CCN heterocyclic ring. Mechanistic studies through rotating ring-disk electrode and radical tests demonstrated that C-CCN0.7 follows the associative 2e- pathway with H2O2 selectivity of 70 %. As such, this research casts insights into tailoring C-doping to regulate the formation of specific functional groups toward boosted photoredox activity of CCN photocatalysts.

MXene has been the limelight for studies on electrode active materials, aiming at developing supercapacitors with boosted energy density to meet the emerging influx of wearable and portable electronic devices. Despite its various desirable properties including intrinsic flexibility, high specific surface area, excellent metallic conductivity and unique abundance of surface functionalities, its full potential for electrochemical performance is hindered by the notorious restacking phenomenon of MXene nanosheets. Ascribed to its two-dimensional (2D) nature and surface functional groups, inevitable Van der Waals interactions drive the agglomeration of nanosheets, ultimately reducing the exposure of electrochemically active sites to the electrolyte, as well as severely lengthening electrolyte ion transport pathways. As a result, energy and power density deteriorate, limiting the application versatility of MXene-based supercapacitors. Constructing 3D architectures using 2D nanosheets presents as a straightforward yet ingenious approach to mitigate the fatal flaws of MXene. However, the sheer number of distinct methodologies reported, thus far, calls for a systematic review that unravels the rationale behind such 3D MXene structural designs. Herein, this review aims to serve this purpose while also scrutinizing the structure-property relationship to correlate such structural modifications to their ensuing electrochemical performance enhancements. Besides, the physicochemical properties of MXene play fundamental roles in determining the effective charge storage capabilities of 3D MXene-based electrodes. This largely depends on different MXene synthesis techniques and synthesis condition variations, hence, elucidated in this review as well. Lastly, the challenges and perspectives for achieving viable commercialization of MXene-based supercapacitor electrodes are highlighted.