Tungsten-liquid triboelectric nanogenerator for water-flowing energy harvesting with low-resistance and high-DC density

In the new energy era, triboelectric nanogenerator (TENG) effectively converts weak water energy into electricity to drive sensors and electronic components, which has a very broad research prospect. However, the functional materials of TENG are usually insulating, resulting in low-current and high-resistance problems. Guided by Wang's electrical double layer model, we demonstrate that tungsten presents excellent electricity generation performance in flowing water due to its unique defect structure as evidenced by comparing the electricity generation of tungsten, tantalum, titanium, and copper, and testing their electrochemical impedance spectroscopy and X-ray diffraction characteristics. Hence, the study proposes a novel tungsten-liquid TENG for water-flowing energy harvesting, which has outstanding advantages of high DC density, low internal resistance, simple structure, and no complex electrical power required. A tungsten-liquid TENG continuously outputs 3∼20μA in 0.1–2.0M NaCl liquids at a flow rate of 400 mL/min, with output current densities up to 230 mA/m2 and internal resistances down to 6.4–67 kΩ. Ten-tungsten-liquid TENG outputs nearly 40μA, and multiple tungsten electrodes in parallel can effectively enhance the current. Notably, the study is not only beneficial for capturing the current energy in oceans with high-ionic concentrations, but also broadens the research ideas of TENG for promoting the selection of novel functional materials.