The oxygen functionalization of carbon materials has widely been employed to improve the catalytic performance of carbon-supported Pt (Pt/C) catalysts. Hydrochloric acid (HCl) has often been employed to clean carbons during the preparation of carbon materials. However, the effect of oxygen functionalization through a HCl treatment of porous carbon (PC) supports on the performance of the alkaline hydrogen evolution reaction (HER) has rarely been investigated. Herein, the impact of HCl combined with the heat treatment of PC supports on the HER performance of Pt/C catalysts has been comprehensively investigated. The structural characterizations revealed similar structures of pristine and modified PC. Nevertheless, the HCl treatment resulted in abundant hydroxyl and carboxyl groups and the further heat treatment formed thermally stable carbonyl and ether groups. Among the catalysts, Pt loading on the HCl-treated PC followed by a heat treatment at 700 °C (Pt/PC-H-700) exhibited elevated HER activity with a lower overpotential of 50 mV at 10 mA cm−2 when compared to the unmodified Pt/PC (89 mV). Pt/PC-H-700 also exhibited better durability than the Pt/PC. Overall, novel insights into the impact of the surface chemistry properties of porous carbon supports on the HER performance of Pt/C catalysts were provided, which were useful for highlighting the feasible improvement of HER performances by regulating the surface oxygen species of porous carbon supports.

No abstract

As electrode materials for zinc ion capacitors (ZICs), porous carbons are an important factor affecting the electrochemical behavior of ZICs. Heteroatom doping is an efficient approach to adjust the pore structure, regulate the electronic structure, increase the surface wettability, and provide pseudo capacitance. In this work, hierarchical porous N/S codoped activated carbon (N/S-AC) materials were prepared from lignin using urea and thiourea as the dopants. The preparation process consisted of first step charring and second step activation with codoping to yield N/S-AC, which exhibited hierarchical pore structure, suitable for providing abundant active sites. The use of N/S-AC as cathode materials for ZIC delivered an outstanding specific capacitance of 307 F g–1 at 1 A g–1 and a remarkable capacity retention of 99.72% after 20,000 cycles at 10 A g–1. The device also exhibited a high energy density of 108.8 Wh kg–1 at 2880 W kg–1 and 65.8 Wh kg–1 at 115200 W kg–1. The excellent electrochemical properties were attributed to the synergistic effect of nitrogen and sulfur elements, and hierarchical porous structure. In sum, these findings are promising for development of ZIC electrode materials with high energy density.

No abstract

N-doped nanoporous carbon (NPC) has widely been used as electrode materials for supercapacitors owing to its high specific capacitance, superior rate capability, and long-life cycling performance. However, exploring the charge distribution mechanism of NPC with various types of N species under different charged states remains challenging. Herein, NPC derived from petroleum coke was prepared by the KOH activation method. The electrochemical testing suggested satisfactory capacitance performance of the as-obtained edge-N-dominated nanoporous carbon. An assembled symmetric supercapacitor device in a 6 M KOH electrolyte delivered a specific capacitance reaching 220 F g–1 at a current density of 1 A g–1, a value 37.5% higher than that obtained by pristine carbon (160 F g–1). The theoretical calculation results demonstrated a high adsorption capacity of edge-N toward K+. The increase in net charge on the electrode materials led to the accumulation of electrons on N-dopants, forming a negative charge center relevant to strengthening K+ adsorption. Overall, insights into the effect of N species on charge distribution in different charged states were provided, conducive to guiding the large-scale development of supercapacitors and other energy storage devices.