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nondestructive detection, [2] material identification, [3] biomedical sensing, [4] to the emerging sixth generation (6G) communications, [5] in which THz absorbers with high absorption intensity (>99%) in a large qualified bandwidth are urgently demanded. THz absorber can be widely used in THz emitting/detecting antennas to reduce the sidelobe radiation or any undesirable radiation, or in the whole THz systems to suppress the electromagnetic interference (EMI). [6,7] Another potential use is for radar cross-section (RCS) reduction, which can reduce radar echo to achieve a greater element of stealth. [8] Considering that THz imaging system has already been commercialized, [9,10] THz communication have been officially designated for 6G network, [11-13] and even the prototype of THz radar have been demonstrated for concealed weapon detection, [14-16] there is being an urgent and huge demand of high-intensity absorption, broadband, and low cost THz absorber in both military and civilian aspects. Generally, condensed materials with higher conductivity inherently have higher electromagnetic (EM) loss, which, however, does not guarantee a stronger absorption because higher conductivity in turn leads to stronger reflection at the surface of material. When EM wave radiates from free space to a condensed material, the reflection from the surface is nearly inevitable to occur unless the impedance matching is achieved,

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