Bionic evaporators inspired by natural plants like bamboo and mushrooms have emerged as efficient generators through water capillary evaporation. However, primitive natural evaporators cannot currently meet growing demand, and their performance limitations remain largely unexplored, presenting a substantial challenge. Through extensive experimentation and detailed simulation analysis, this study presents a precisely engineered H-type bamboo steam generator. This innovative design incorporates a unique node structure embedded with graphite flakes and an internode characterized by micro- and nanoporous channels, all achieved through streamlined carbonization. The results are striking: a water evaporation rate of 2.28 kg m-2 h-1 and a photothermal conversion efficiency of 90.2% under one-sun irradiation, outperforming comparable alternatives. This study also marks the first comprehensive simulation in COMSOL modeling water capillary evaporation, driven by the synergistic effects of photothermal graphitic layers, broad-spectrum solar absorption, and capillary microstructures. The chimney-assisted, enclosed cavity structure further enhances water capillary evaporation and thermal localization. This breakthrough not only enables efficient use of waste biomass but also advances the field of sustainable materials, opening new avenues in solar-driven steam generation.