Abstract:

To improve the solar-thermal conversion efficiency of biomass carbonized rice husk，the transition metal catalytic technique was proposed to regulate the pyrolytic carbon structure of carbonized rice husk and optimize the solar steam generation performance.Firstly，a typical porous rice husk foam was constructed with introducing nickel nitrate as a catalyst precursor.And then，the graphitized carbon modified carbonized rice husk foam（GC/CRF） absorber was prepared by employing transition metal Ni as catalyst to in-situ catalyze the pyrolytic carbon of rice husk graphitizing during the carbonation process.The structure，light absorption and solar steam generation performance of GC/CRF were investigated.It was showed that the prepared GC/CRF availably retained the three-dimensional porous structure of original rice husk foam with pore sizes range from 10~100 µm，and Ni catalyst was uniformly dispersed in the foam structure.By the catalysis of Ni，large numbers of core-shell nanospheres were also formed in the absorber，with nano Ni as core and graphitized carbon layer as shell.The formation of graphitized carbon showed positive effect on improving the graphitization degree of GC/CRF，so as to enhance the light absorption and solar steam generation performance.After carbonizing at 1 200 ℃，the GC/CRF absorber achieved maximum absorption and solar-vapor evaporation efficiency with values up to ~94% and ~70%.

Key words: transition metal catalyst, carbonized rice husk foam, graphitized carbon, solar steam generation