Performance enhancement of moisture diffusion energy harvesters by means of cobalt mixing and PVA coating of biochar

IF 7 2区生物学 Q1 AGRICULTURAL ENGINEERING

Biomass & Bioenergy Pub Date : 2026-08-01 Epub Date: 2026-03-07 DOI:10.1016/j.biombioe.2026.109236

Hyeonoh Hwang , Ahmed Muhammad Ajaz , Xuanjun Jin , Azma Fakhar , Joon Weon Choi

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Abstract

Moisture-diffusion energy harvesters (MDEHs) convert the transport of moisture and evaporation within porous electrodes into electrical output, providing a direct sensing-to-power pathway for water-leak detection and monitoring applications. Here, we report a biochar-based MDEH that integrates cobalt (Co) mixing and sequential poly vinyl alcohol (PVA) coating as complementary strategies to regulate interfacial charge transport and moisture management. Structure-optimized oak mushroom logwood (OML) biochar was prepared via KOH activation (700 °C), short-duration dry milling (5 min), and HNO₃ oxidation (5 M, 3 h), followed by aqueous Co impregnation (5–20 wt%) and drop-cast PVA coating (9 wt%, 1–4 mL). Although Co incorporation reduced BET surface area and mesoporosity, it significantly enhanced charge generation and transport, increasing the short-circuit current (Isc) from 18.7 ± 4.7 μA (control) to 44.1 ± 0.4 μA (Co20) and the open-circuit voltage (Voc) from 333 ± 7 to 368 ± 15 mV. The subsequent PVA coating infiltrated and bridged the fibrous scaffold, moderating capillary wetting dynamics (from 3 s to 35–45 s) and stabilizing the moisture gradient, thereby improving voltage reproducibility and extending the output duration. An intermediate coating level (PVA2) provided the optimal current-voltage balance, achieving an Isc of 39.2 ± 0.7 μA and a Voc of 572 ± 22 mV. Finally, Co20-PVA2-MDEH was assembled into a 25-strip array and integrated with an energy-harvesting power management integrated circuit and capacitive storage to enable intermittent, battery-free Bluetooth Low Energy advertising (10 s per cycle), demonstrating a practical self-powered module for real-time water-leak sensing.

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钴混合和生物炭PVA涂层增强湿扩散能量收集器性能

水分扩散能量采集器（mdeh）将多孔电极内的水分传输和蒸发转化为电力输出，为水泄漏检测和监测应用提供了直接的传感-供电途径。在这里，我们报道了一种基于生物炭的MDEH，它集成了钴（Co）混合和顺序聚乙烯醇（PVA）涂层，作为调节界面电荷传输和水分管理的互补策略。通过KOH活化（700°C），短时间干磨（5 min）， HNO3氧化（5 M, 3 h），然后是Co水浸（5 - 20 wt%）和PVA滴投涂层（9 wt%, 1-4 mL）制备结构优化的橡木原木（OML）生物炭。Co的掺入虽然降低了BET的表面积和介孔率，但显著增强了电荷的产生和输运，使短路电流（Isc）从对照（18.7±4.7 μA）增加到44.1±0.4 μA (Co20)，开路电压（Voc）从333±7增加到368±15 mV。随后的PVA涂层渗透并桥接纤维支架，减缓了毛细管润湿动力学（从3秒到35-45秒），稳定了水分梯度，从而提高了电压的再现性，延长了输出时间。中间涂层层（PVA2）提供了最佳的电流-电压平衡，Isc为39.2±0.7 μA， Voc为572±22 mV。最后，将Co20-PVA2-MDEH组装成一个25条阵列，并与能量收集电源管理集成电路和电容存储集成在一起，实现间歇性，无电池蓝牙低功耗广告（每周期10秒），展示了一个实用的自供电模块，用于实时漏水检测。

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来源期刊

Biomass & Bioenergy 工程技术-能源与燃料

CiteScore

11.50

自引率

3.30%

发文量

258

审稿时长

60 days

期刊介绍： Biomass & Bioenergy is an international journal publishing original research papers and short communications, review articles and case studies on biological resources, chemical and biological processes, and biomass products for new renewable sources of energy and materials. The scope of the journal extends to the environmental, management and economic aspects of biomass and bioenergy. Key areas covered by the journal: • Biomass: sources, energy crop production processes, genetic improvements, composition. Please note that research on these biomass subjects must be linked directly to bioenergy generation. • Biological Residues: residues/rests from agricultural production, forestry and plantations (palm, sugar etc), processing industries, and municipal sources (MSW). Papers on the use of biomass residues through innovative processes/technological novelty and/or consideration of feedstock/system sustainability (or unsustainability) are welcomed. However waste treatment processes and pollution control or mitigation which are only tangentially related to bioenergy are not in the scope of the journal, as they are more suited to publications in the environmental arena. Papers that describe conventional waste streams (ie well described in existing literature) that do not empirically address ''new'' added value from the process are not suitable for submission to the journal. • Bioenergy Processes: fermentations, thermochemical conversions, liquid and gaseous fuels, and petrochemical substitutes • Bioenergy Utilization: direct combustion, gasification, electricity production, chemical processes, and by-product remediation • Biomass and the Environment: carbon cycle, the net energy efficiency of bioenergy systems, assessment of sustainability, and biodiversity issues.