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Recently, the growing demand for a renewable and sustainable fuel alternative is contingent on fuel cell technologies. Even though it is regarded as an environmentally sustainable method of generating fuel for immediate concerns, it must be enhanced to make it extraordinarily affordable, and environmentally sustainable. Hydrogen (H2) synthesis by electrochemical water splitting (ECWS) is considered one of the foremost potential prospective methods for renewable energy output and H2 society implementation. Existing massive H2 output is mostly reliant on the steaming reformation of carbon fuels that yield CO2 together with H2 and is a finite resource. ECWS is a viable, efficient, and contamination‐free method for H2 evolution. Consequently, developing reliable and cost‐effective technology for ECWS was a top priority for scientists around the globe. Utilizing renewable technologies to decrease total fuel utilization is crucial for H2 evolution. Capturing and transforming the fuel from the ambient through various renewable solutions for water splitting (WS) could effectively reduce the need for additional electricity. ECWS is among the foremost potential prospective methods for renewable energy output and the achievement of a H2‐based economy. For the overall water splitting (OWS), several transition‐metal‐based polyfunctional metal catalysts for both cathode and anode have been synthesized. Furthermore, the essential to the widespread adoption of such technology is the development of reduced‐price, super functional electrocatalysts to substitute those, depending on metals. Many metal‐premised electrocatalysts for both the anode and cathode have been designed for the WS process. The attributes of H2 and oxygen (O2) dynamics interactions on the electrodes of water electrolysis cells and the fundamental techniques for evaluating the achievement of electrocatalysts are outlined in this paper. Special emphasis is paid to their fabrication, electrocatalytic performance, durability, and measures for enhancing their efficiency. In addition, prospective ideas on metal‐based WS electrocatalysts based on existing problems are presented. It is anticipated that this review will offer a straight direction toward the engineering and construction of novel polyfunctional electrocatalysts encompassing superior efficiency in a suitable WS technique. [ABSTRACT FROM AUTHOR]

Summary: Conjugated monomer 2,6‐dimethylindole (DMI) was integrated into the triazine framework of polymeric carbon nitride (PCN) via molecular engineering. As‐prepared samples were utilized for photocatalytic evolution of hydrogen (H2) through water splitting and photodegradation of RhB dye under visible light. The integration of this monomer DMI has been dominated within the internal framework of PCN and operated as a substitution reaction membrane, retarding an appropriate control and promote the charge density in π‐electron conjugated system. It also promotes the charge transferring and separation to elevate the photocatalytic activity of PCN under visible light. The HER for pure PCN was found as 77.9 μmol/h, while for PCN‐DMI18.0 was predicted at 701.2 μmol/h, which is exclusively output approximately nine times higher than that of pure PCN respectively. Besides, the pseudo‐order kinetic constant of PCN‐DMI18.0 degradation of RhB was multiple times higher when contrasted to pristine PCN. [ABSTRACT FROM AUTHOR]

Recently, the graphite based heterogeneous photocatalysts has attained tremendous research attention in various environmental applications. Among them, the graphitic carbon nitride (g-C 3 N 4) is categorized as a unique solar active particle with its outstanding intrinsic properties i.e., adequate band configuration, excellent light absorptivity and thermo-physical durability, which make it highly useful and reliable for revenue transformation and ecological concerns. Considering the intrinsic potential of g-C 3 N 4 in photocatalysis, so far, no report has been done in literature for its extraordinary configuration, morphological characteristics and perspective tuning for said applications. To overcome this research gap, our primary emphasis of this review regarding photocatalysis is to provide layout as well as the advancement of visible-light-fueled materials as highly stabilized and extremely effective ones for pragmatic implementation. Thus, this existing comprehensive assessment conducts a systematic survey over visible light driven non-metal novel g-C 3 N 4. The major advancement of this evaluation is the fabrication of well-designed nanosized g-C 3 N 4 photocatalysts with unique configurable frameworks and compositions. Furthermore, alternative techniques in order to customize the analogue band configuration and noticeable cultivation such as metal (cation), nonmetal (anion) doping, worthy metal activating, and alloy initiation with certain semiconductors are discussed in detail. In addition to this, g-C 3 N 4 photocatalytic functionalities towards photocatalytic hydrogen evolution, CO 2 photoreduction, biological metal ions deterioration as well as bacterial sanitization are also presented and discussed in detail. Therefore, we believe that such a pivotal compact assessment can provide a roadmap in several perspectives on the currently underway obstacles in the innovation of effective g-C 3 N 4 catalytic design processes. Moreover, this critical assessment will ultimately serve as a useful supplement in the research area of g-C 3 N 4 nanosized photocatalysts and for the researchers working on its key aspects in diverse range of natural, chemistry, engineering and environmental applications. • Graphitic carbon nitride (g-C 3 N 4) is a metal-free sustainable photocatalyst with a band gap of 2.7 eV. • G-C 3 N 4 has improved light absorption performance as well as electronic features. • Multiple synthetic approaches are being used with g-C 3 N 4 to improve its photocatalytic capabilities. • Metals/nonmetals doping, activation, and alloy formation are employed for g-C 3 N 4 nanocomposites. • Our review includes the latest current g-C 3 N 4 nanocomposites and their photocatalytic implications. [ABSTRACT FROM AUTHOR]

The carbon nitride (CN) has good stability, a comprehensive band structure, and a more straightforward fabrication process that makes them a top candidate for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). So far, scientists have been involved broadly in utilizing smaller carbon-based molecules to modify the CN framework for better-quality solar to fuel energy conversion. Still, the modification of material with a natural macromolecule has been explored insufficiently. In this regard, we firstly a copolymerized carbon nitride (CNP x) by conjugating a novel monomer 2,6-dibenzolumazine with CN through molecular integration (CNP x). The copolymerized catalysts demonstrated noteworthy improvement in photocatalytic activities as compared to pristine CN. Following this, we further combine our superior sample (CNP 5.0) with the underlying biomass-based lignin molecules forming CNP-L x. The biomass-modified CNP-L x obtained through this process has an increased HER and OER under visible light (λ=420 nm). Findings demonstrate the catalytic performance seven times higher for CNP-L x and three times enhanced for CNP x sample than CN catalyst. These improvements can be attributed to the ultrathin nanostructure and efficient visible light absorption of the CN, well-balanced exciton states of the organic monomer, and the synergetic effect of lignin synergetic effect on its surface. Lignin-activated CNP 5.0 photocatalysts produced through this method can prove cost-effective and efficient alternatives for solar overall water splitting. A proposed graphical scheme on conduction band (CB) and valence band (VB) utilizing lignin modified copolymerized CNP for overall water splitting under visible light illumination. [Display omitted] [ABSTRACT FROM AUTHOR]