My current researches are synthesis and analysis of functional nano(bio)-materials for environmentally friendly energy applications, such as photo/electro/betavoltaics and heterogeneous photo/bio/electro catalysts. In this seminar I would like to introduce 4 major research topics in my research group. (1) CO$_2$ is a heat absorbing greenhouse gas; more CO$_2$ in the atmosphere corresponds to a hotter planet with corresponding desertification of arable lands and rising sea levels. Efficient, stable, and readily synthesized CO$_2$-reduction photocatalysts will be introduced. (2) Microbial fuel cells (MFCs) received considerable attention because of their ability to provide dual advantages of electricity generation and wastewater treatment. However, their performance is primarily limited by the slow oxygen reduction reaction (ORR). To alleviate this problem, we report a hybrid MFC in which a conventional bioanode is coupled with a TiO$_2$ photoanode. (3) Acupuncture as a therapeutic intervention has been widely used for treatment of many pathophysiological disorders. So motivated, we have developed a new class of acupuncture needles, porous acupuncture needles (PANs) with hierarchical micro/nano-scale conical pores upon the surface. The performance of these high-surface-area PANs is more effective in controlling electrophysiological and behavioral responses than conventional acupuncture needles. (4) Over the past several decades there has been extensive research and development of solar cell technologies. Herein, we report on a dye-sensitized betavoltaic cell (DSBC), a new addition to aforementioned technologies, which successfully integrates two different technologies: dye-sensitized photovoltaics and beta particle excitation.