There maybe has oxide of copper in the surface of nano copper catalyst particles.

在纳米螺旋碳纤维中的催化剂颗粒表层，可能有铜的氧化物存在。

youdao

While cerium oxide is a rare Earth element, it is one of the more common ones. Its abundance has been compared to copper.

氧化铈是一种较常见的稀土元素，其储存量可以与铜相媲美。

youdao

2 mg of copper as cupric oxide.

铜氧化物中铜质2毫克。

youdao

Thus all those mountains of copper oxide out there (and there are many, quite literally, mountains of copper oxide) became copper ore instead of dirt.

FORBES: But Why Did Julian Simon Win The Paul Ehrlich Bet?

While this may have been good news for Nepal, Indian industry claims the market was flooded with exports of hydrogenated vegetable oil, acrylic yarns, iron pipes, copper wire and zinc oxide, which India claims has hurt its market.

BBC: India, Nepal prepare for trade talks