The escalating issue of global water pollution, driven by an array of emerging pollutants, necessitates effective treatment strategies. Among various approaches, catalytic peroxymonosulfate (PMS) activation technology stands out, particularly utilizing modified biochar as a catalyst. Metal-heteroatom-co-doped biochar (MH-BC) is emerging as a superior catalyst due to its synergistic effects that enhance PMS activation, surpassing the performance of solely heteroatom-doped or metal-doped biochars.

This review highlights the innovative pathways in fabricating MH-BC, focusing on internal versus external doping and pre- versus post-modification techniques. It delves into the critical parameters influencing MH-BC’s efficacy as a PMS activator, such as the source of precursors, synthesis methods, and conditions. An extensive overview of PMS activation pathways facilitated by MH-BC is presented, illustrating its versatility and efficiency in generating various reactive species like hydroxyl, sulfate, superoxide radicals, singlet oxygen, and high-valent oxo species.

The ability of MH-BC to catalyze PMS and generate reactive species efficiently is critically analyzed, including the mechanisms of radical generation and the conditions under which these reactions are optimized. However, challenges remain, such as the stability of MH-BC, the complex interactions between metal and heteroatom during activation, and the difficulty in quantifying radicals in multi-radical oxidative systems.

In conclusion, while MH-BC represents a promising advancement in the field of water treatment technologies, further research is required to overcome its limitations and fully understand the intricate dynamics of its catalytic behavior. This understanding will be crucial in paving the way for its application in large-scale environmental remediation and sustainable water management practices.