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Switching to renewable, carbon-neutral sources of energy is urgent and critical for climate change mitigation. Despite how hydrogen production by electrolyzing water can enable renewable energy storage, current technologies unfortunately require rare and expensive platinum group metal electrocatalysts, which limit their economic viability. Transition metal dichalcogenides (TMDs) are low-cost, earth-abundant materials that possess the potential to replace platinum as the hydrogen evolution catalyst for water electrolysis, but so far, pristine TMDs are plagued by poor catalytic performances. Defect engineering is an attractive approach to enhance the catalytic efficiency of TMDs and is not subjected to the limitations of other approaches like phase engineering and surface structure engineering. In this minireview, we discuss the recent progress made in defect-engineered TMDs as efficient, robust, and low-cost catalysts for water splitting. The roles of chalcogen atomic defects in engineering TMDs for improvements to the hydrogen evolution reaction (HER) are summarized. Finally, we highlight our perspectives on the challenges and opportunities of defect engineering in TMDs for electrocatalytic water splitting. We hope to provide inspirations for designing the state-of-the-art catalysts for future breakthroughs in the electrocatalytic HER. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) National Research Foundation (NRF) Published version X.Y.K. acknowledges that this research is funded by the Singapore National Academy of Science (SNAS) and the National Research Foundation (NRF) of Singapore under the SNAS ASEAN Fellowship Program (NRF-MP-2020-0001). H.S.S. acknowledges that this project is supported by A*STAR under the AME IRG grant no. A2083c0050. H.S.S. is also grateful for the Singapore Ministry of Education Academic Research Fund Tier 1 grants RT 05/19 and RG 09/22, and the NTU 5th ACE Grant Call. S.-P.C. thanked the Ministry of Higher Education (MOHE) Malaysia for supporting this work under the Malaysia Research University Network (MRUN) (Project No. 304/PJKIMIA/656501/829 K145).

This state-of-the-art review of MXene-based catalysts in CO2 electro/photoreduction places an emphasis on synthesis approaches, surface termination modulation, heterostructure engineering and reaction mechanisms.

In this study, graphitic carbon nitride (CN) decorated with carbon quantum dot (CQD) and bismuth oxychlorobromide (BiOCl

Project Management in Information System (IS) or Information Technology (IT) is one of the fastest-growing industries in developed countries. Cloud-based applications are an upcoming trend compared to on-premise software development, and a large sum of money is being poured into the industry to improve productivity and production efficiency. In Malaysia, most agricultural-based activities continue to use traditional methods that can be quite time-consuming for farmers or breeders. Thus, it can be impossible to gain accurate real-time insights needed for smart farming. Conventionally, the data collected by hand must be entered manually into computers for historical record and reference, resulting in additional efforts (rework) and inefficiency. In this study, a cloud-based Bee-Smart system was developed to optimize the maintenance and monitoring of bee farms. The core of the system is a cloud-based maintenance solution and progress report for stingless bee collection data. It not only reduces farmers’ paperwork, but also gives them easy access to the historical records of each hive on a farm, based on hive activity and nectar sources in the area. The prototype was then piloted in BoDen Edu Farm where the applicability of the smart systems was proven to be effective. &nbsp

Photocatalysis is a perennial solution that promises to resolve deep-rooted challenges related to environmental pollution and energy deficit through harvesting the inexhaustible and renewable solar energy. To date, a cornucopia of photocatalytic materials has been investigated with the research wave presently steered by the development of novel, affordable, and effective metal-free semiconductors with fascinating physicochemical and semiconducting characteristics. Coincidentally, the recently emerged red phosphorus (RP) semiconductor finds itself fitting perfectly into this category ascribed to its earth abundant, low-cost, and metal-free nature. More notably, the renowned red allotrope of the phosphorus family is spectacularly bestowed with strengthened optical absorption features, propitious electronic band configuration, and ease of functionalization and modification as well as high stability. Comprehensively detailing RP's roles and implications in photocatalysis, this review article will first include information on different RP allotropes and their chemical structures, followed by the meticulous scrutiny of their physicochemical and semiconducting properties such as electronic band structure, optical absorption features, and charge carrier dynamics. Besides that, state-of-the-art synthesis strategies for developing various RP allotropes and RP-based photocatalytic systems will also be outlined. In addition, modification or functionalization of RP with other semiconductors for promoting effective photocatalytic applications will be discussed to assess its versatility and feasibility as a high-performing photocatalytic system. Lastly, the challenges facing RP photocatalysts and future research directions will be included to propel the feasible development of RP-based systems with considerably augmented photocatalytic efficiency. This review article aspires to facilitate the rational development of multifunctional RP-based photocatalytic systems by widening the cognizance of rational engineering as well as to fine-tune the electronic, optical, and charge carrier properties of RP.

The interactions of CO2 with terrace, step, and defect or kink sites on Pt surfaces were investigated using temperature-programmed desorption, X-ray photoelectron spectroscopy, and density function...

Research on advanced materials for environmental remediation and pollutant degradation is rapidly progressing because of their numerous applications. Biochar is an excellent material support for the catalytic activity of bismuth ferrite (BiFeO3), which is one of the best perovskite-based photocatalysts in this work for diverse pollutant degradation when exposed to direct sunlight. Biochar was produced by pyrolyzing oil palm empty fruit bunches (OPEFBs) and then integrate with BiFeO3 in the presence of cross-linked chitosan to create a BFO/biochar coupled magnetic photocatalyst (CBB). This research was conducted to examine the performance of the photocatalytic activity of CBB towards the degradation of ciprofloxacin antibiotics. To determine the optimal condition, two operational parameters that are photocatalyst dosage and initial pollutant concentrations, were evaluated. The results of the powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope-energy dispersive X-ray (SEM-EDX) analyses confirmed the high purity of the rhombohedral BiFeO3 with a high surface area, as well as the successful coupling of BiFeO3 and biochar at a ratio of 1:1. The most effective conditions for the various variables are 1.5 g/L CBB dosage at 10 ppm with 77.08% photodegradation under direct sunlight for 2 h. Further, a pseudo-first-order kinetic reaction was followed and observed with decreasing k values as the initial concentration increased. This shows that the system performs best at low concentrations. This finding confirms that the catalytic parameters improved the efficiency of photocatalysts with biochar assistance in removing antibiotic pollutants.

Nitric oxide (NO) as the major constituent of nitrogen oxides (NOx), which is mainly emitted from combustion processes, is responsible for several environmental and health issues, and the control of its emission is a global concern. In this regard, this study investigates low-temperature oxidative uptake of NO on alkali-modified biochar. Rubber seed shell was utilized as a locally available lignocellulosic waste to develop biochar through slow pyrolysis. The porosity attributes and surface chemistry of the developed biochar were then improved through alkali modification. The NO capture capacity of KOH, NaOH, K2CO3 and Na2CO3-activated biochars was 63.0, 59.3, 59.0 and 58.5 mg/g, respectively, which was considerably higher than that of the pristine biochar, 17.8 mg/g. This considerable improvement was mainly attributed to the introduction of more oxygen functionalities, improvement of microporosity and creation of more carbon defects in the biochar, after alkali modification. With some investigations on the alkali agent/biochar impregnation ratio, the adsorption capacity of the KOH-activated biochar (at a ratio of 2:1 (w/w)) could be improved to 87.0 mg/g at 30 °C. Characterization studies using FTIR and XPS suggested that the adsorbed species on the biochar surface was in the form of monodentate nitrito (–O–N=O), which was formed from the oxidation of NO on the surface-oxidized groups. Kinetic studies using pseudo-first, pseudo-second and Elovich models indicated that the adsorption of NO on KOH-activated biochar surface was mainly controlled by a physisorption or a weak chemisorption process, with a low activation energy of − 29 kJ/mol.

The novel hematite (α-Fe2O3)/nickel oxide (NiO) heterostructures were grown on fluorine-doped tin oxide (FTO) coated glass substrates at various deposited NiO of 3, 5, and 7 layers. The heterostructures were successfully synthesized using the immersion and sol–gel spin coating methods for α-Fe2O3 and NiO films, respectively. The field emission scanning electron microscopy analysis showed that each sample of α-Fe2O3/NiO heterostructures has a unique surface morphology when deposited with different NiO layers. The X-ray diffraction pattern shows that the number of NiO layers affected the diffraction peaks. The NiO diffraction peak intensity at (111) plane increased when the deposition number of NiO layer was increased. The crystallite sizes of NiO were 35.4, 33.6, and 38.0 nm for 3-, 5-, and 7-layer NiO, respectively. The interplanar spacing, lattice parameter, and unit cell volume indicate NiO with 3-layer as the highest, while 5- and 7-layer had the same values. Meanwhile, the strain and stress values show the compressive strain and tensile stress, respectively. The optical properties reveal that the highest transmittance and the lowest absorbance percentages were recorded for a 3-layer NiO sample. In contrast, the lowest transmittance and the highest absorbance percentages were obtained for the sample with 5-layer NiO. Different thicknesses and morphologies of heterostructures explained these situations. In addition, each unique heterostructure of α-Fe2O3/NiO with high visible light absorption nature is perceived to reduce the bandgap energy and has the potential to be used in sensor and solar cell applications.

Thermodynamic assessment and experimental investigation on the formation of titanium hydride (TiH2) from the reaction between titanium tetrachloride (TiCl4) gas and magnesium hydride (MgH2) powder were carried out under hydrogen atmosphere. In this new method, the production of TiH2 powder at low temperature was investigated, which can be used for further dehydrogenation process to produce low-cost Ti powder. In this work, the effects of temperature, time, amount of titanium trifluoride (TiF3) as a catalyst, and ball-milling time of the MgH2 on the formation of TiH2 were investigated. The phase transformations and evolution of the morphology of the powders with an increase in time and temperature were studied by x-ray diffraction and scanning electron microscopy, respectively. The results of the reaction at 400 °C for 10 h indicated that producing TiH2 from the reduction of TiCl4 with MgH2 at low temperature was feasible and has a significant potential for the low-cost synthesis method of TiH2 for Ti powder production.

Two dimensional (2D) reduced-graphene-oxide/g-C3N4 modified 2D ZnV2O6 heterojunction for enhanced photocatalytic CO2 reduction has been investigated. The catalysts were fabricated using one-pot solvothermal method and were tested in a fixed-bed reactor under visible and UV-light. The ZnV2O6/RGO/g-C3N4 composite catalyst demonstrated excellent photoactivity for CO2 reduction to CO and hydrocarbons under visible light. The maximum CO yield rate of 2802.9 μmol g−1 h−1 was obtained over the composite, which is 7.4 and 1.7 times higher than using g-C3N4 and ZnV2O6, respectively. The improved activity attributing to synergistic effect of 2D layer heterojunction with enhanced charges separation by RGO mediator under visible light. Comparatively, 2 times lower productivity was obtained under UV-light than visible-light due to higher visible-light absorption. The time-dependent kinetic-model was further developed to understand the influence of photocatalytic oxidation and reduction processes on the reaction chemistry. The model is based on Langmuir–Hinshelwood (L–H) mechanism to understand the formation rates of products during photocatalytic CO2 conversion with water vapours. Kinetic reveals surface reaction is a rate limiting step, which depends on the generation of charge carrier with higher light absorption. The findings from the experimental and kinetic-model would be useful to understand photo-catalytic reaction engineering in solar energy applications.

In this work, the novel utilisation of customised double- and triple-tail sodium bis(3,5,5-trimethyl-1-hexyl) sulphosuccinate (AOT4) and sodium 1,4-bis(neopentyloxy)-3-(neopentyloxycarbonyl)-1,4-dioxobutane-2-silphonate (TC14) surfactants to assist the direct graphene oxide (GO) synthesis via electrochemical exfoliation utilising dimethylacetamide (DMAc) as a solvent were investigated. The synthesised DMAc-based GO and titanium dioxide (TiO2) nanoparticles were then used to fabricate polyvinylidene fluoride (PVDF)-based nanofiltration (NF) membranes by the non-solvent-induced phase separation method. The incorporation of GO and TiO2 as hydrophilic nanoparticles were to enhance membrane hydrophilicity. The utilisation of higher surfactants’ tail number obviously alters the fabricated membrane’s morphology which further affects its performance for dye rejection and antifouling ability. Higher surfactants’ tail number resulted in higher oxidation process which then provided more interaction between the GO and PVDF. Based on the dead-end cell measurement, PVDF/TC14-GO/TiO2 presented a slightly higher dye rejection efficiency of 92.61% as compared to PVDF/AOT4-GO/TiO2 membrane (92.39%). However, PVDF/TC14-GO/TiO2 possessed three times higher water permeability (48.968 L/m2 h MPa) than PVDF/AOT4-GO/TiO2 (16.533 L/m2 h MPa) and also higher hydrophilicity as presented by lower contact angle (65.4 ± 0.17°). This confirmed that higher surfactants’ tail number improved the fabricated membrane’s performance. Both fabricated membranes also exhibited high flux recovery ratio (FRR) ( $$>$$ 100%) which indicated better antifouling properties.

This study investigates the co-gasification of tire char (TC), as a low-quality side-product of scrap tire pyrolysis, and rambutan peel (RP). The objective of this study was to comprehend any synergistic/antagonistic effects during the co-gasification of TC/RP. For this, co-gasification of TC and RP (85:15, 70:30, 50:50, 30:70, and 15:85 wt% of TC:RP) was conducted in CO2 environment by non-isothermal thermogravimetric method. The samples were heated (15 K/min) under N2 to 923 K and then under CO2 to 1400 K. Comparison of the observed and theoretical results indicated the incidence of antagonism in blends with high proportion of TC (e.g., 85%TC–15%RP and 70%TC–30%RP), possibly attributing to the high content of acid oxides (SO3 (30.1%) and SiO2 (24.8%)) in the TC-ash which could inhibit the gasification by formation of inactive silicates in the presence of alkali/alkaline earth metal-rich biomass. In blends with higher content of biomass (e.g., 30%TC–70%RP and 15%TC–85%RP), the actual gasification rates were higher than the theoretically predicted ones showing the presence of a synergism associated with the natural catalysts (K2O (40.6%) and CaO (42.3%)) in RP-ash. Activation energy and thermodynamic studies confirmed the profound effect of biomass on enhancing the reactivity of TC in reaction with CO2. These promoting effects of biomass were associated with its considerably higher alkali index (133.4) than tire (5.6), its less graphitic structure with more structural defects, and imperfections compared with TC. According to the results, the inherently low reactivity of TC in gasification can be accelerated by co-feeding of biomass with TC.

This study explored the potential of In2O3/ZrO2 catalyst for direct CO2 hydrogenation to methanol. Despite the excellent properties proven by density functional theory (DFT) studies, the experimental works on this catalyst are still very limited. In this study, In2O3/ZrO2 catalysts were synthesized via wetness impregnation (In2O3/ZrO2(WI)), citric acid-based sol-gel method (In2O3/ZrO2(SG)) and deposition-precipitation assisted by urea hydrolysis (In2O3/ZrO2(UH)). Results indicated the impressive effect of preparation method on the catalytic activity where In2O3/ZrO2(SG) presented superior catalytic performance, followed by In2O3/ZrO2(UH) and In2O3/ZrO2(WI), with the CO2 conversion of 16.23%, methanol selectivity of 94.39% and STY of 0.95 gmethanol/gcat·h. To unravel the structure-function relationship, several characterization techniques including XRD, HR-TEM, SEM-EDX, H2-TPR, CO2-TPD, N2 adsorption-desorption isotherm and XPS were implemented to analyze the developed catalysts. The analyses indicated that the excellent performance of In2O3/ZrO2 (SG) was due to its smaller crystallite size, strong metal-support interaction, high reducibility and high concentration of basic sites and oxygen vacancies on the catalyst surface. Time-on-stream stability test showed that In2O3/ZrO2 (SG) catalyst could sustain its high activity and selectivity within 100 h, signifying the high potential of this catalyst for direct hydrogenation of CO2 to methanol with minimum side reactions and deactivation.

Several multi-walled carbon nanotubes supported Ni-Ce catalysts were synthesized, and their performance in carbon dioxide reforming of methane (CDRM) for syngas production was evaluated. The attachment of Ni-Ce nanoparticles to the functionalized carbon nanotube (fCNT) support was carried out using four synthesis routes, i.e., impregnation (I), sol-gel (S), co-precipitation (C), and hydrothermal (H) methods. Results indicated that synthesis method influences the properties of the NiCe/fCNT catalysts in terms of homogeneity of metal dispersion, size of crystallites, and metal-support interaction. The activity of the catalysts followed the order of NiCe/fCNT(H) > NiCe/fCNT(S) > NiCe/fCNT(C) > NiCe/fCNT(I). The NiCe/fCNT(H) catalyst exhibited the highest catalytic activity with CH4 and CO2 conversions of 92 and 96%, respectively, and resulted in syngas product with consistent H2/CO ratio of 0.91 at reaction temperature of 800 °C without notable deactivation up to 30 h of reaction. Moreover, the growth of carbon on the spent catalyst was only 2% with deposition rate of 4.08 mg/gcat·h; this was plausibly due to the well-dispersed distribution of nanoparticles on fCNT surface and abundant presence of oxygenated groups on the catalyst surface.

Photocatalytic CO2 reduction is a revolutionary approach to solve imminent energy and environmental issues by replicating the ingenuity of nature. The past decade has witnessed an impetus in the rise of two-dimensional (2D) structure materials as advanced nanomaterials to boost photocatalytic activities. In particular, the use of 2D carbon-based materials is deemed as highly favorable, not only as a green material choice, but also due to their exceptional physicochemical and electrical properties. This Review article presents a diverse range of alterations and compositions derived from 2D carbon-based nanomaterials, mainly graphene and graphitic carbon nitride (g-C3 N4 ), which have remarkably ameliorated the photocatalytic CO2 performance. Herein, the rational design of the photocatalyst systems with consideration of the aspect of dimensionality and the resultant heterostructures at the interface are systematically analyzed to elucidate an insightful perspective on this pacey subject. Finally, a conclusion and outlook on the limitations and prospects of the cutting-edge research field are highlighted.