Considering the problems of environmental pollution and treatment costs generated by renewable waste biomass on a global scale, the development of high-performance electrodes utilizing plentiful natural waste biomass as sustainable precursors is essential to facilitate the practical application of supercapacitors. Hence, we develop a facile and efficient method to construct waste bamboo shavings into petal-like hierarchical porous carbon electrode materials with an ultrahigh specific surface area and N, O codoped interfaces through H 3 PO 4 -catalyzed hydrothermal pretreatment combined with coactivation by KOH/melamine. The effects of optimal regulation of pore structure and surface modification (heteroatom doping) on the superior electrochemical properties of carbon materials are investigated in depth. The derived carbon materials presenting an excellent potential for practical applications of supercapacitors are mainly attributed to their large specific surface area (3392 m 2 g −1 ), prominent pore volume (2.081 m 3 g −1 ), and petal-like hierarchical porous structure with abundant N, O content, which results in rapid ion diffusion and adequate electrical charge storage as well as contributed pseudocapacitance. 5-BHPC-700-4 exhibits attractive electrochemical properties in a 6.0 M KOH electrolyte, including a delightful capacitance (501.6 F g −1 at 0.5 A g −1 in a three-electrode system) and superior cycling stability (94.2% capacitance retention after 10,000 cycles at 5.0 A g −1 ). The assembled symmetrical supercapacitor device achieves an impressive energy density of 15.3 Wh kg −1 at a power density of 290 W kg −1 . This work provides a valuable reference for the design and preparation of biomass-based hierarchical porous carbon with outstanding supercapacitor performance and low cost.

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Although transition metal materials are extensively studied for hydrogen evolution reaction (HER) because of their intrinsic electrochemical properties, their practical applications have been hindered by low conductivity, unsatisfactory activity, and poor stability. To develop an approach for practical applications, it is imperative to improve their electrocatalytic performance. Herein, we report the fabrication of hollow NiMoP nanopetals embedded with Ndoped carbon dots (CDs) by a simple hydrothermal method. The addition of CDs can effectively modulate the morphology, reduce aggregation, and maintain long-term stability. Impressively, the optimal Ni 5 Mo 3 P@CDs 3 exhibits excellent HER performance, in terms of a low overpotential of 183 mV at 10 mA cm −2 , small Tafel slope of 41.04 mV dec −1 , high conductivity, and remarkable long-term stability in acidic media for HER. This work opens an effective avenue to construct excellent property and accessible electrocatalysts for HER with the assistance of CDs.

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A large amount of coal gasification slag is produced every year in China. However, most of the current disposal is into landfills, which causes serious harm to the environment. In this research, coal gasification fine slag residual carbon porous material (GFSA) was prepared using gasification fine slag foam flotation obtained carbon residue (GFSF) as raw material and an adsorbent to carry out an adsorption test on waste liquid containing methylene blue (MB). The effects of activation parameters (GFSF/KOH ratio mass ratio, activation temperature, and activation time) on the cation exchange capacity (CEC) of GFSA were investigated. The total specific surface area and pore volume of GSFA with the highest CEC were 574.02 m2/g and 0.467 cm3/g, respectively. The degree of pore formation had an important effect on CEC. The maximum adsorption capacity of GFSA on MB was 19.18 mg/g in the MB adsorption test. The effects of pH, adsorption time, amount of adsorbent, and initial MB concentration on adsorption efficiency were studied. Langmuir isotherm and quasi second-order kinetic model have a good fitting effect on the adsorption isotherm and kinetic model of MB.