Biochars derived from PN and WS were prepared in a patented biochar reactor (NO. ZL2009 2 0232191.9) under oxygen-limited conditions. According to the decomposition rule of the feedstocks obtained from thermal analysis, 350 °C and 550 °C were selected as the pyrolysis temperatures (See Supplementary S2). To remove the ash on biochars, HCl/HF (1.0 M, v/v 1:1) solution was used to wash the raw biochars for several times. The details for biochar preparation were shown in Supplementary S2. The biochar sample derived from PN (WS) at 350 °C and 550 °C were denoted as PN350 (WS350) and PN550 (WS550), respectively. The de-ashed biochar were denoted as PN350D, PN550D, WS350D, and WS550D.