# Ionic Highways under Multivariate‐Coupled Strategies: Ultrahigh Power Generation from Industrial Waste Liquors Using Robust COF Membranes

## TL;DR

This paper introduces a new membrane that efficiently generates energy from industrial waste by combining heat, acidity, and salinity.

## Contribution

A robust COF membrane with tunable charge density for ultrahigh power generation in harsh industrial conditions.

## Key findings

- The membrane achieves 258.81 W m−2 power output, 52 times higher than commercial benchmarks.
- The β-ketoenamine linkage ensures stability under thermal, chemical, and electrochemical stresses.
- Low-grade heat and acidity synergistically enhance ion transport and power generation.

## Abstract

Efficiently harvesting the intrinsic energy from low‐grade heat, acidity, and high salinity of desulfurization waste liquors is crucial for sustainable management, yet remains challenging due to the instability of conventional membranes under such extreme multi‐physics conditions. Herein, we report a high‐performance osmotic energy conversion device engineered via a multivariate coupling strategy. The core of this device is a robust membrane based on β‐ketoenamine‐linked covalent organic frameworks (COFs), featuring nanochannels functionalized with tailored stimuli‐responsive groups to dynamically regulate surface charge density. The β‐ketoenamine linkage endows exceptional membrane stability, enabling durable operation under coupled thermal, chemical, and electrochemical stresses. Experimental and computational studies demonstrate that the remarkable power enhancement stems not only from acid‐induced protonation that boosts charge density, but also from the utilization of low‐grade heat to accelerate ion transport. By simulating the multi‐physical field coupling in real waste liquors, the device achieves an ultrahigh power output of 258.81 W m−
2, surpassing commercial benchmarks by 52‐fold. This COF membrane, with its exceptional permeability, selectivity, and stability, paves the way for high‐efficiency energy harvesting from hostile industrial environments.

This study presents a multivariate‐coupled strategy to fabricate TB‐COF membranes with tunable charge density via uniformly distributed Bpy groups, enabling efficient ion transport and energy harvesting. The robust β‐ketoenamine‐linked structure ensures stability, achieving power outputs of 53.08 W m−2 (pH 4), 190.52 W m−2 (low‐grade heat), and 258.81 W m−2 (acid / heat). The designed membranes exhibit exceptional ion selectivity and permeability, enabling high‐performance nanofluidic energy harvesting devices.