為了有效提升氫能的使用效率與發展，氫氣的儲存是一項極具挑戰且必須的研發方向，減少儲存材料上的成本以及低溫儲存所要求之能耗，奈米氫氣泡的儲氫概念被學者提出，有別於傳統之氫氣儲存方式，同時藉由Young-Laplace equation可得知，奈米氫氣泡因為奈米尺度的氣泡粒徑，呈現內壓高的自主高壓之優勢，將氫氣以奈米氣泡之方式儲存作為新一代氣體儲存翻開嶄新的一頁。為了穩定氣泡的存活，以高比表面積之吸附質作為氣泡載體是為一項極具潛力的方向。同時，為了使奈米氫氣泡能夠穩定存在，本研究嘗試使用奈米活性碳材料作為氣泡吸附以及包覆的目標物，活性碳以被廣泛應用於氣相吸附的實際操作，在氫氣吸附的研究領域更是有著卓越的表現，近年來，為達到美國國家能源局(Department of Energy)所訂定之 5.5 wt % 的儲氫效能，質量輕的碳材料再次吸引研究焦點。
本研究透過水熱碳化(Hydrothermal Carbonization)法所形成之鎳摻雜碳奈米球，經過物理/化學活化反應，合成出吸附性極佳、高比表面積且碳顆粒粒徑維持在50 ± 10奈米之鎳摻雜活性碳奈米球，零模板的合成法(Template-free method)簡化了製程同時省去大量材料成本。
於液氮冷卻一大氣壓之氫氣壓力下，鎳摻雜奈米碳球之氫氣氣相吸附效能可達2.8 wt %，鎳金屬的化學吸附能力輔以高空隙率之活性碳奈米球的物理吸附，相較於比較面積相當的其他儲氫材料例如製程較複雜之有機金屬框架、以及儲氫量較不穩定的合金─金屬氫化物，有著相當的儲氫效能，但在製程上與材料成本上碳奈米球則佔極大優勢。
相較於以往的儲氫研究，其研究重點多著重於氫氣液化以提高能量密度，且多以吸附力較強的化學吸附作為主要儲氫驅動力，氫氣在儲存後的釋放步驟往往需要高溫環境作為驅使，進而產生另外的能耗，本研究透過水熱碳化合成，一步驟合成鎳摻雜碳奈米球，在低溫常壓下呈現高水平的儲氫能力，顯示出極佳的氣象吸附能力，用以作為奈米氫氣泡吸附體的一項潛力選擇。

In order to effectively improve the utilization and development of hydrogen source, hydrogen storage has become challenging research pathway, in terms of reducing the cost of storage materials and the required energy consumption at low-temperature. Hence, hydrogen nano bubble storage technology has been proposed by researchers. Different from traditional hydrogen storage method, hydrogen nano bubble storage can be explained in term of Young-Laplace equation, in which the nano scale of particles encourages hydrogen gas to be stored at higher internal pressure without external processing, thus become state-of-the-art in current hydrogen storage. To maintain the stability of hydrogen bubble, adsorption on high specific surface area as a bubble carrier is a promising pathway in expanding this development. Besides, this study attempts to choose nano-activated carbon materials an efficient hydrogen adsorbent material to design gas storage systems. To date, activated carbon is widely used for gas-phase adsorption due to its excellent performance in storing gas at higher capacity and lower price, especially for hydrogen adsorption. Obeying the report by US Department of Energy, light-weight carbon becomes potential materials to achieve 5.5 wt% hydrogen storage, further getting attention for future development.
In this study, nickel-doped carbon nanospheres were synthesized from hydrothermal carbonization method. With the aid of physical and chemical activation, the carbon adsorbent exhibits excellent adsorption, high specific surface area and carbon particle in the size range 40–60 nm. In additional, the application of the template-free method simplifies the synthesis process and saves a large amount of material costs.
In summary, the hydrogen gas phase adsorption efficiency of nickel-doped nano carbon spheres can reach 2.8 wt % under the atmospheric pressure in liquid nitrogen environment. The metallic nickel component of adsorbent contributes to chemical adsorption, while the physical adsorption is facilitated by high void ratio of activated carbon nanospheres. Comparing to other material with comparable hydrogen storage, such as organometallic frameworks with complex processes, and alloys or metal hydrides with lower stability in hydrogen storage, nickel-doped carbon nanospheres still shows greater advantages in terms of processing and material cost.
Compared with the previous hydrogen storage research, the focus is more on hydrogen liquefaction to increase energy density, and stronger chemical adsorption has been interpreted as the main driving force for hydrogen storage. Hence, the desorption step of hydrogen is necessary to be conducted under high temperature environment for this condition, thus then generating additional energy consumption. This study focus on the synthesis of nickel-doped carbon nanospheres through one step hydrothermal carbonization process, and exhibited high levels of hydrogen storage capacity under low temperature and normal pressure. It shows excellent gas-phase adsorption capacity, hence act as a potential choice for nano hydrogen bubble adsorbent.

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