ABSTRACT The electrochemical reduction of carbon dioxide (CO 2 RR) to usable fuels and chemicals is one of the most prospective green and sustainable strategies to achieve worldwide carbon management. However, finding efficient and cost‐effective electrocatalysts that can achieve high energy and Faradaic efficiencies, as well as facilitating fast and selective conversion, remains a significant challenge. Porous carbon doped with earth‐abundant metals and non‐metals are highly promising cathodes for CO 2 RR due to their low cost, outstanding surface area, high electrical conductivity, and accessible active sites, in addition to ease of high‐mass production from earth‐abundant resources. Consequently, a wide range of strategies have been developed for the rational synthesis of porous doped carbon materials with diverse morphologies and compositions for CO 2 electroreduction into gaseous and liquid products. Given the rapid advancements and growing interest in this field, timely updates are essential to guiding future research and development. This review provides a comprehensive overview of porous carbon nanostructures functionalized with transition metals and p‐block metals (e.g., Ni, Fe, Cu, Mn, Co, Zn, In, Bi, Sn) as well as non‐metal dopants (e.g., S, F, B, P), including their hybrid configurations. We highlight how the spatial arrangement and electronic interactions of metal/non‐metal species influence CO 2 RR performance, and we discuss fundamental aspects such as reaction mechanisms, active site modulation, and reactor designs. Special attention is given to dual‐site and multi‐metallic systems, which often exhibit synergistic effects beyond those of their single‐metal counterparts. The review concludes with a critical outlook on the challenges and opportunities in designing next‐generation CO 2 RR electrocatalysts through precise control over porous carbon–metal interfaces.

Developing Pt-free electrocatalysts is the main solution for reducing the intolerable cost of hydrogen production through the hydrogen evolution reaction (HER), while sustaining rare-earth elements. Thus, we have synthesized carbon nanoflakes derived from carbon cloth doped with controllable boron atoms (Bx/C), where x refers to boron atomic contents (x = 3.42, 5.04, 9.79, and 14.64 wt.%), driven by the impregnation of carbon cloth containing polyester (CC) in an aqueous solution of boric acid, followed by drying at 80 °C for 1 h and then calcination at 500 °C for 2 h under nitrogen. The method allows the conversion of one-dimensional CC to a two-dimensional flake-like structure, in situ enriched with B-C motifs as active sites for HER. The HER performance depends on interfacial interaction of boron with carbon, but B1/C (B = 3.42 wt %) was the optimum with a HER current of 370 mA/cm2 at -0.78 V, overpotential at 10 mA/cm2 (ƞHER@10) of 372 mV, Tafel slope of 166 mV/dec, and stability for 60 h, besides a hydrogen production rate of 1.57 mol·g-1·h-1 of catalyst, due to endowing surface area, intermolecular charge transfer, and electrical conductivity. The data obtained may pave the way for designing heteroatom-integrated carbon from biomass for promoting low-cost HER.

Exploring Pt-free electrocatalysts for hydrogen evolution reaction (HER) is crucial for achieving low-cost hydrogen production. Herein, we present a facile one-pot approach for coconut-driven hierarchical porous carbon nanofibers (h-CNFs) encapsulated metal nanocrystals (M/h-CNFs) (M = Co, Cu, W, Mo, and Bi) by direct impregnation of coconut fibers in metal precursors solution followed by carbonization under argon. Coconut fiber with its rich built-in ether (C-O-C) and hydroxyl (OH) groups, can act as a source for carbon and as a rector to drive the scalable production (several grams) of ultra-long (similar to 100-500 mu m) hierarchical porous nanofibers (multimodal pores), well-distribution of tiny metal nanocrystals (10-20 nm) active sites, and high surface area (275.8 m(2)/g). These merits endowed the electrocatalytic HER performance of M/h-CNFs significantly higher than metal-free h-CNFs, but Co/h-CNFs and Cu/h-CNFs revealed activities close to the commercial Pt/C (10 wt % Pt) catalyst with a current density (similar to 300 mA/cm(2)), low overpotential of (154 mV), and H-2 production rate of (19.5 mol g(-1)& centerdot;h(-1)), although low metal content (i.e., similar to 10 wt %). This study is evidence for paving the way for the conversion of coconut fiber wastes to a cost-effective catalyst for HER.

Porous carbons derived from sugarcane (CSC) encapsulated with silver nanocrystals (Agₓ/CSC) were synthesized with tunable Ag loadings (x): 16.2 wt% (Ag₁/CSC), 10.1 wt% (Ag₀.₅/CSC), and 6.1 wt% (Ag₀.₁/CSC) by direct impregnation of sugarcane bagasse in aqueous AgNO₃ under ultrasonication, followed by drying and annealing. During ultrasonication, acoustic cavitation and in situ released gases (H₂, H₂O) facilitate Ag+ ions reduction without reducing agents, making the method eco-friendly and energy-efficient. The acoustic cavitation mechanism driven by ultrasonication process facilitates the rapid reduction of Ag+ ions and promotes the uniform dispersion of Ag nanocrystals within the CSC matrix. The resulting Ag₁/CSC composite exhibits semispherical Ag nanocrystals well dispersed on a porous, aligned carbon tube structure with a high surface area (212.6 m2/g) and excellent conductivity. These features significantly enhance electrocatalytic oxidation and sensing of ascorbic acid compared to Ag-free CSC. Among all composites, Ag₁/CSC showed the best performance, with a mass activity of 15 mA/mg and durability over 2000 cycles. It also demonstrated a wide linear detection range (10 μM to 50 mM), a low detection limit (0.755 μM), a sensitivity of 34 μA mM−1 cm−2, and a fast response time (2–3 s). These improvements are attributed to its high electrochemical surface area, superior conductivity, and well-dispersed Ag nanocrystals. This work opens new avenues for CSC-supported metal nanocrystals in electrochemical detection of small organic molecules.

Silicon carbide (SiC) and silicon nanoparticle-decorated carbon (Si/C) materials are electrodes that can potentially be used in various rechargeable batteries, owing to their inimitable merits, including non-flammability, stability, eco-friendly nature, low cost, outstanding theoretical capacity, and earth abundance. However, SiC has inferior electrical conductivity, volume expansion, a low Li+ diffusion rate during charge–discharge, and inevitable repeated formation of a solid–electrolyte interface layer, which hinders its commercial utilization. To address these issues, extensive research has focused on optimizing preparation methods, engineering morphology, doping, and creating composites with other additives (such as carbon materials, metal oxides, nitrides, chalcogenides, polymers, and alloys). Owing to the upsurge in this research arena, providing timely updates on the use of SiC and Si/C for batteries is of great importance. This review summarizes the controlled design of SiC-based and Si/C composites using various methods for rechargeable metal-ion batteries like lithium-ion (LIBs), sodium-ion (SIBs), zinc-air (ZnBs), and potassium-ion batteries (PIBs). The experimental and predicted theoretical performance of SiC composites that incorporate various carbon materials, nanocrystals, and non-metal dopants are summarized. In addition, a brief synopsis of the current challenges and prospects is provided to highlight potential research directions for SiC composites in batteries.

Developing Pt-free electrocatalysts for overall water splitting over wide pH values is one of the main roadmaps to decrease hydrogen and oxygen production costs, but it remains a grand challenge. This study presents the promoting of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performance of SiC nanoparticles by doping with oxygen (SiC-Ox) (x =O-content 4.94 wt% in SiC-O1 and 8.4 wt% in SiC-O2). The preparation method encounters a modified microwave method to prepare SiC nanocrystals and then impregnation and calcination under air to endow the formation of SiC-Ox enriched with oxygen vacancies. The as-made materials SiC and Si-Ox were characterized using various techniques like SEM, XRD, and XPS, which showed that SiC-Ox had a particle size of nearly 52.5-55 nm, a surface area of 58.8-65.5 m2/g, and was enriched with tunable oxygen content. The HER and OER performance of SiC-Ox was superior to undoped SiC nanocrystals over universal pH at least two times, but SiC-O1 was the optimum in H2SO4 and KOH electrolytes. Mainly, SiC-O1 delivered HER current density (305 mA/cm2) with an overpotential of 313 mV and H2 production rate of 3.1 mol g-1 h-1 rate in H2SO4, besides OER current density of 67 mA/cm2 and overpotential of 0.98 V in H2SO4 in addition to OER current of 67.65 mA/cm2 and overpotential of 0.99 V in KOH. This is due to proper oxygen doping, higher surface area, lower charge transfer resistance, and improved electrical conductivity of SiC-O1. These findings can open new gates for using oxygen-enriched metal carbide to promote electrocatalytic watersplitting activity.

Biomass-based engineered hierarchical porous carbons derived from biomass waste are deemed cost-effective and sustainable materials for supercapacitors, thanks to their tunable properties, e.g., high conductivity, and stability; however, their multiple preparation steps and low capacitance are deemed significant challenges. These issues were addressed herein through the rational design of hierarchical porous carbon nanotubes (p-CNTs) enriched with metal nanocrystals (M/p-CNTs) (M=Cu, Co, W, Bi, and Mo) via the ultrasonic impregnation of coconut silks in metal precursor solutions and pyrolysis under nitrogen. This approach promotes a green, one-pot method that eliminates the need for activation steps or hazardous chemicals, and endows the formation of nanotubes through a strong-metal carbon interaction, resulting in metal electron-deficiency, with a BET surface area of 288.6 m2/g, along with interconnected tri-modal porosity, which accelerates charge mobility and facilitates ion transport. These advantages significantly improved the performance of supercapacitors, which was fine-tuned by the intermolecular electron transfer between metals and p-CNTs, which reached the optimum specific capacitance of 558.1F/g at 0.5 A/g, energy density of 27.9 Wh/kg, and power density of 150/3000 W/kg at 1/10 A/g on Cu/p-CNTs, which was amongst highest reported for active supercapacitors. These findings pave the way for the simple and sustainable synthesis of active materials from biomass for energy storage devices.

Engineering structural defects is beneficial for electrocatalytic performances. Herein, a class of acid-etched PtNiRh nanotubes with abundant structural defects around cavities were constructed. Modulated electronic and coordination structures closely associated with structural defects boost the ethanol oxidation reaction (EOR) activity and selectivity. The optimized PtNiRh-E-H nanotubes exhibit an EOR mass and specific activity of 1.81 A mgPt -1 and 3.38 mA cm-2, respectively. A high retention at 1.80 A mgPt -1 after a chronoamperometric test of 10000 s was achieved by PtNiRh-E-H nanotubes. Moreover, the PtNiRh-E-H nanotubes featuring compressive lattice strain and lower-lying d band center display a strong inclination for the C1 pathway, as evidenced by a higher linearly bonded CO band intensity and lower intensity of adsorbed acetate across the applied potentials using attenuated total-reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS). Also, the attenuated CO adsorption and accelerated CO oxidative desorption by OH species led to superior C1 selectivity of the PtNiRh-E-H nanotubes. Differential mass spectrometry (DEMS) together with ATR-SEIRAS provides explicit evidence of catalytic pathway as CH3CH2OH -> CH3CH2OHads -> -> CH3CHO -> CH3CO -> CH3 + CO -> 2CO2. The work represents a feasible strategy for alcohol oxidation catalysis, wherein acid etching exposes significantly more structural defects and brings about an optimal electronic structure and lattice strain.

Green hydrogen (H2) production through hydrogen evolution reaction (HER) via water splitting is deemed an efficient and sustainable fuel or energy carrier without environmental detriments. However, its higher cost remains the bottleneck in the commercialization process. Ubiquitously, porous binary metal-based catalysts so far remain the most active electrocatalysts for the HER, owing to their electronic effect, optimum hydrogen binding energy, and lower activation energies for H-desorption and recombination close to the thermodynamic potential. Despite plentiful efforts and developments, the engineering of porous binary metals for the HER still comprises numerous scientific problems to be unraveled, which still await deliberation. This review emphasizes the rational design of porous noble binary-metal-based electrocatalysts, porous transition binary-metal electrocatalysts (i.e., carbides/oxides, phosphides, chalcogenides) for the HER, both experimentally and theoretically (i.e., density functional theory (DFT) simulations and machine learning). Additionally, the associated mechanism, fundamental, and current interrogations (i.e., electronic effect, phase, strain, phase engineering, and interaction support) are highlighted related to porous bimetallic electrocatalysts for the HER. Eventually, a brief synopsis of the relevant milestones of current challenges and revitalizing perspectives to direct future research is presented aimed at developing effective porous binary metal-based electrocatalysts for large-scale HER applications.

The presented data emphasizes the significant effect of oxygen doping on promoting the electrocatalytic activity and durability of silicon carbide (SiC) nanoparticles towards water electrolysis, including oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in different electrolytes. This data is particularly relevant for researchers in academia, industrial representatives, and other parties who are focused on enhancing the electrocatalytic properties of metal carbides or semiconductors used in electrochemical energy conversion and production reactions. The XRD calculations herein are important for understanding the effect of doping on the crystallinity of metal carbide. The OER and HER durability tests are crucial for investigating the feasibility of the as-made SiC for partial applications. These data are related to the research article titled ‘’Oxygen-Enriched Silicon Carbide Nanocrystals for Efficient Overall Water Splitting: Unveiling Effect of Doping and Electrolyte pH.’’

Porous SnO2 nanostructures have garnered tremendous attention for detecting volatile organic compounds due to their high surface area, oxygen vacancies, and massive adsorption and diffusion sites for gases. However, the effect of porosity and support on the ethanol-sensing behavior of SnO2 still needs to be clarified. Herein, porous SnO2 nanostructures supported on reduced graphene (SnO2/rGO) were synthesized via the hydrothermal method, followed by annealing at different temperatures under air. The hydrothermal method with annealing at 500 degrees C endowed the formation of spatial hierarchical porous SnO2 microspheres (HMP-SnO2-500) composed of small nanoflakes, but at 300 degrees C, aggregated microspheres with less porosity (HMP-SnO2-300) were formed, and hydrothermal alone yielded aggregated flakes on rGO nanosheets (SnO2/rGO). The porosity and crystallinity of SnO2 improved significantly after annealing at 500 degrees C under air, and the particle size also decreased. Thereby, the ethanol sensing properties of HMP-SnO2-500 were higher than those of HMP-SnO2-300, SnO2/rGO, and SnO2, with a detection limit of 0-3000 ppm, a quick response time of 5-20 s, fast recovery, long-term durability (12 days), and outstanding sensitivity in the presence of different volatile organic materials. This is due to the hierarchical porosity, high surface area, higher electrical conductivity, and synergetic effect of HMP-SnO2-500, which may open new gates for the rational design of self-standing or supported porous SnO2 nanostructures for efficient sensing of organic materials.

A facile approach is presented for the scalable generation of porous, ultralong carbon nitride nanoscrolls as electrocatalysts for electrochemical hydrogen storage and evolution. Activation of C3N4 by subpotential reduction reveals a new material that stores and finally evolves hydrogen, with a performance being superior to Platinum. The optimized system displays an overpotential (η10 = 7 mV) close to commercial Pt/C but provides a superior current density (up to ≈1.3 A cm-2), turnover frequency, HER rate, and higher stability. Additionally, at underpotential conditions, ≈1.5 wt.% activated hydrogen can be stored at ambient pressure and room temperature in such materials.

Porous Pd-based electrocatalysts are promising materials for alkaline direct ethanol fuel cells (ADEFCs) and ethanol sensors in the development of renewable energy and point-of-contact ethanol sensor test kits for drunk drivers. However, experimental and theoretical investigations of the interfacial interaction among Pd nanocrystals on supports (i.e., carbon black (CB), onion-like carbon (OLC), and CeO2/OLC) toward ADEFC and ethanol sensors are not yet reported. This is based on the preparation of Pd-CeO2/OLC nanocrystals by the sol-gel and impregnation methods. Evidently, the porous Pd-CeO2/OLC significantly increased membrane-free micro-3D-printed ADEFC performance with a high peak power density (P-max = 27.15 mW cm(-2)) that is 1.38- and 7.58-times those of Pd/OLC (19.72 mW cm(-2)) and Pd/CB (3.59 mW cm(-2)), besides its excellent stability for 48 h. This is due to the excellent interfacial interaction among Pd, CeO2, and OLC, evidenced by density functional theory (DFT) simulations that showed a modulated Pd d-band center and facile active oxygenated species formation by the CeO2 needed for ethanol fuel cells. Similarly, Pd-CeO2/OLC gives excellent sensitivity (0.00024 mA mM(-1)) and limit of detection (LoD = 8.7 mM) for ethanol sensing and satisfactory recoveries (89-108%) in commercial alcoholic beverages (i.e., human serum, Amstel beer, and Nederberg Wine). This study shows the excellent possibility of utilizing Pd-CeO2/OLC for future applications in fuel cells and alcohol sensors.

Porous Pt-based alloys entail earth-abundant and low-cost metal, not only contribute to the rational consumption of expensive and rare Pt metal but also the enhancement of its activity towards the methanol electro-oxidation reaction (MEOR). Herein, a porous sponge-like PtPb alloy was synthesized by using the ice-reduction method driven by the coalescence growth mechanism under the intensive reduction power of borohydride. The presented PtPb sponge nanostructure was prepared using a facile, one-step method without heating or surfactants. Meanwhile, PtPb had a sponge-like shape with accessible active sites, a high surface area, abundant pore volume (0.05 cm3/g), pore size (2-20 nm), Pb loading (13.0 at.%), and an upshifted d-band center of Pt. These inimitable structural and compositional merits endow the electro-oxidation of methanol with a higher mass (specific) activity of 0.907 mA/mu gPt (5.7 mA/cm2) compared to those of Pt sponge-like nanostructure and Pt/C catalyst by 1.47 (1.35) and 1.72 (8.51) times, respectively, besides higher durability. Moreover, PtPb had higher activity and durability towards the electro-oxidation of carbon monoxide (CO) than Pt and Pt/C. The proposed study may provide new insights into the simple synthesis of a Pt-based alloy for the electrocatalytic oxidation of small organic molecules.

The rechargeable alkali metal-ion batteries (RAMIBs) are highly promising candidates for next-generation efficient energy storage devices, owing to their outstanding theoretical specific capacities and extremely low electrochemical potentials. However, RAMIBs possess unsuitable lifespans, low mechanical durability and inevitable side reactions attributable to their inherent severe volumetric/structure alteration during the charge-discharge cycles. These hitches could be solved using porous multimetallic alloy-based anodes, due to their impressive specific capacities, low working potential, low cost, and earth-abundance, which can meet sustainability and practical application needs. Meanwhile, great surface area, electrical conductivity, structural stability, and ability to accommodate the generated alkali metal ions can yield satisfactory coulomb efficiency and long durability. Immense efforts are dedicated to rationally designing porous multimetallic alloy-based anodes for RAMIBs, so it is essential to provide timely updates on this research area. Herein, we reviewed recent advances in porous multimetallic alloy-based anodes (i.e., Sn, Mn, Mo, Co, V, and Fe) for RAMIBs (i.e., lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries. This is rooted in the engineering approaches (i.e., template-based, hydrothermal/solvothermal, chemical reduction, electrochemical deposition, sol-gel, and electrospinning) to fundamental insights (i.e., mechanisms, key parameters, and calculations) and precise evaluation for structural changes, and mechanisms by various experimental, theoretical, and in-situ analysis to optimizing their performance. Also, advances in RAMIBs recycling and circular economy were discussed. Eventually, we highlighted the current drawbacks and provided proposed perspectives to solve these issues and enable practical utilization of such anodes for large-scale applications.

Porous one-dimensional Pt-based alloys with outstanding specific surface areas, short electron transport paths, and accessible Pt atoms are potential electrocatalysts for methanol oxidation reaction (MOR); however, their simple one-step synthesis for MOR remains a challenge. In this study, a simple one-step method is presented for the rational fabrication of PtPb porous nanowires (PNWs) by the direct autoclave of binary metal precursors in the mixed solvent of ethylene glycol and N,N-dimethylformamide at 170 degrees C. The formation of PtPb PNWs is driven by the autocatalytic and Ostwald ripening growth mechanism with the assistance of ethylene glycol and N,N-dimethylformamide as a solvent, in situ template, and reducing agent. This method forms PtPb porous ultra-long (similar to 1.5 mu m) neural PNWs with an average width of 20 nm enriched with abundant pores (5-10 nm), high Pb content (29 wt%), and decreased d-band level of Pt. These unique structural features enhanced the MOR mass (specific) activity of PtPb PNWs of 4.39 mA/mu g(Pt) (49.3 mA/cm(2)) by 4.5 (9.6) and 5.5 (35.0) times than those of Pt PNWs and Pt/C catalyst, respectively besides higher durability and CO-tolerance. The MOR activity of PtPb PNWs was among the highest reported binary porous Pt-based catalysts, which may promote the preparation of other Pt alloys PNWs for MOR.

Metal–organic framework-derived porous N/Co-doped carbon (MOF-PNC) anchored sponge-like Pd–SnO 2 nanoparticles (Pd–SnO 2 /MOF-PNC), prepared by microwave-irradiation, annealing and chemical etching, delivered excellent low-temperature carbon monoxide oxidation.

Tailored morphology of porous binary Pt-based nanostructures is a powerful way to improve their catalytic properties. Herein, we develop a facile aqueous solution approach for the rational one-step synthesis of PtAg nanochains via direct nucleation followed by the oriented attachment growth mechanism under sonication at room temperature. This allows the green and simple fabrication of PtAg wavy nanochains (200 nm length and 20 nm width) with spatially interconnected pores (10 nm) and a high surface area (55.02 m 2 /g). These merits endowed the methanol oxidation reaction (MOR) performance of PtAg nanochains with a mass activity of (1.12 mA/ mu g Pt ) that was about 1.83, 2.8, and 3.11 times higher than those of PtAg nanodendrites, Pt nanodendrites, and commercial Pt/C, respectively, owing to porous nanochain morphology and alloying effect. Intriguingly, visible-light irradiation enhances the MOR performance of PtAg nanochain by nearly 1.5 times, owing to its great photoelectric response properties. The MOR activity of PtAg nanochains is among the highest reported Pt-based electrocatalysts. The presented method may open new edges on the rational design of porous Pt-based nanoarchitecture for various catalytic applications.

Electrocatalytic hydrogen evolution reactions (HER) are envisaged as the most promising sustainable approach for green hydrogen production. However, the considerably high cost often associated with such reactions, particularly upon scale-up, poses a daunting challenge. Herein, a facile, effective, and environmentally benign one-pot scalable approach is developed to fabricate MnM (M & boxH;Co, Cu, Ni, and Fe) nanocrystals supported over in situ formed carbon nanofibers (MnM/C) as efficient noble-metal-free electrocatalysts for HER. The formation of carbon nanofibers entails impregnating cellulose in an aqueous solution of metal precursors, followed by annealing the mixture at 550 degrees C. During the impregnation process, cellulose acts as a reactor for inducing the in situ reductions of MnM salts with the assistance of ether and hydroxyl groups to drive the mass production (several grams) of ultralong (5 +/- 1 mu M) carbon nanofibers ornamented with MnM nanoparticles (10-14 nm in size) at an average loading of 2.87 wt %. For better electrocatalytic HER benchmarking, the fabricated catalysts were tested over different working electrodes, i.e., carbon paper, carbon foam, and glassy carbon, in the presence of different electrolytes. All the fabricated MnM/C catalysts have demonstrated an appealing synergetic-effect-dependent HER activity, with MnCo/C exhibiting the best performance over carbon foam, close to that of the state-of-the-art commercial Pt/C (10 wt % Pt), with an overpotential of 11 mV at 10 mA cm(-2), a hydrogen production rate of 2448 mol g(-1) h(-1), and a prolonged stability of 2 weeks. The HER performance attained by MnCo/C nanofibers is among the highest reported for Pt-free electrocatalysts, thanks to the mutual alloying effect, higher synergism, large surface area, and active interfacial interactions over the nanofibers. The presented findings underline the potential of our approach for the large-scale production of cost-effective electrocatalysts for practical HER.